Author Topic: DIY Fully Articulating Boom Arm you can make to use with Festool products  (Read 5449 times)

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Offline martin felder

  • Posts: 103
For years, I used the Festool non-articulating boom arm as the massive Festool ASA-5000 was not available in the USA and if it was, it would be a bit much for my shop.  I liked my Festool 203151 compared to no boom arm, but always thought an articulating boom arm would be better (assuming you do not need portability) for my application.  Mounted above cabinets above a workbench with the attached CT-36 below the workbench, no loss of valuable space.  Most importantly, the articulating boom arm with an 8-10 ft extended length offers functional advantages.



In the above picture, on the right, with a swivel non-articulating boom arm, the hose comes down along the arc as shown on the drawing on the right.  If you want to use a tool like a sander not along the arc, the hose has to be at an angle and can pull on the dust port of the tool.  If you have extra length hose to compensate, the hose can drag or lead to the tool wanting to tilt (not good when trying to keep the sander flat) etc.  With an articulating boom arm, the hose comes straight down anywhere at all points along the arc and within the arc (shaded in the center drawing).  That makes it much easier to use over a much wider area and can swivel easily out of the way.  My friend RandyC and I have been working on a DIY homemade boom arm, and here are a few pictures.





This prototype was mounted this past week.  Freely articulates, and no sag.  Just waiting on the hose.  Not expensive to build.  This involved a fair amount of drilling and cutting into aluminum.  I am working on an alternative model where I will try to make the middle section mostly out of wood using 2 inch OD angled thrust bearings and a 2 inch Forstner bit and then we can do a comparison.  It is possible that once we compare these variations, someone with the CNC and machining equipment will be willing to make for others the middle section piece for sale. 

For this DIY shop made boom arm, I hope to soon be providing detailed drawings and step-by-step pictures, and links to where you can buy all of the parts.  The goal is for you to be able to make a fully articulating 8-10 ft boom arm easily at a cost of $200 - $300.  It took a lot of time and some money working on this so that I could have an articulating boom arm myself, and so I figured you could all benefit from my experience with this project.  I have benefitted from advice over the years, and happy to give back.  To be clear, I have no financial interest in this and am not looking to sell anything or profit in any way.  I will keep you posted.

 

Festool USA does not pre-approve the contents of this website nor endorse the application or use of any Festool product in any way other than in the manner described in the Festool Instruction Manual. To reduce the risk of serious injury and/or damage to your Festool product, always read, understand and follow all warnings and instructions in your Festool product's Instruction Manual. Although Festool strives for accuracy in the website material, the website may contain inaccuracies. Festool makes no representations about the accuracy, reliability, completeness or timeliness of the material on this website or about the results to be obtained from using the website. Festool and its affiliates cannot be responsible for improper postings or your reliance on the website's material. Your use of any material contained on this website is entirely at your own risk. The content contained on this site is provided for informational purposes only and does not constitute professional advice.


Offline Bob D.

  • Posts: 1687
Are those gears in the knuckle on the top or bottom? If they are on the bottom they will collect sawdust faster than if up top.

Or you could enclose that whole section with a pleated boot or sock. Just need a piece of sturdy cloth with Velcro strips to fasten it to itself after you wrap it around. Or use magnets sewn into the corners and along the edges.
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It's a table saw, do you know where your fingers are?

Offline martin felder

  • Posts: 103
In these photos, they are on the bottom but could just as easily be located on top.  Thank you for the suggestion.  As for your other suggestion, certainly that is an option, especially if the material can easily stretch.  For the flex hose  for that middle section, I have 2 on order.  1 will compress from 12-6 inches, and a slightly more expensive option will compress 12 to 2 inches.  Whatever is in that section has to be able to stretch-compress. to allow full articulation without resistance.

I am very much an amateur when working on these things, and my friend RandyC who deserves a lot of credit for his contribution to this project, also has no experience designing and making articulating boom arms, and so I am always looking for ways to improve it.

Another option is to not have the bottom pipe for the power cord cord, and drill a number of round holes (eg large forstner bit) along the sides of each arms.   The holes would decrease the weigh and facilitate the threading of the power cord within each segment of the boom arm in the absence of the bottom pipe.  That would save a bit of money on the pipe also, but not look quite as sleek.  Trade off.

Offline ChuckM

  • Posts: 1840
If the hardware and mechanical parts (gear etc.) are available for sale, I 'd be interested even though I have no immediate needs for any boom arm given my shop limitations.

I'm a woodworker and those plywood builds would be a piece of cake to me. I don't even need to run two tubes, just one for the cord and hose together, further reducing the weight or stress on the gears/ bracket, etc. perhaps.

I'm totally not concerned about dust contamination of the gear or whatnot as I can clean up any dust there every time I clean my dust collector and DDs (usually once every two months or three).

Thanks for sharing. I'll monitor this thread for any new updates.
« Last Edit: May 25, 2020, 12:04 AM by ChuckM »

Offline Rchild

  • Posts: 5
This boom arm is hanging up in my shop as of right now.  My concern was sagging of the outer arm.  There is no sag at all now that it's mounted.  It works perfectly.  I'm just waiting for the hose to connect in the middle.  I'm going to run an electrical cord, and air line and the Festool power cord thru the lower pipe and tie onto the vacuum hose.  It will really help with keeping my floor free of cords and hoses and whatnot's..
There's a few improvements I will be working on to make it even better..

Offline martin felder

  • Posts: 103
ChuckM,  what was posted was made in a woodshop using a Kapex and a Powermatic woodworking drill press.  All components were commercially available at the Home Depot or online, and once I experiment with a modification next week to see if certain things in aluminum can be made more easily with wood, RandyC and/or I will post links to where everything can be ordered as far as parts like the gear. 

The goal is for it to be fully functional, well-built and durable, easy and not too time consuming to make with commercially available parts in a woodshop, and inexpensive. 

Offline Bob D.

  • Posts: 1687
Did you consider making the gears from wood? Matthias Wandel has a nice online gear generator app on his web site, or did the last time I visited. You can use it to create templates you can use to make your own gears in any size with as many or as few teeth as you desire (within reason).

Since you are using a box beam type of construction for the arm segments you don't need any structural rigidity in the tubing. There are lighter weight tubes available but not sure if the reduced weight is enough to warrant using them.

Since I live in a rural area every time I go to the dump I watch for someone tossing out an old kids swing set. Some of the pieces will even have well formed bends that could suit dust collection projects. I think that steel tubing used in the construction of those has multiple uses when repurposed. One I have been wanting to build is an overarm dust collection for my table saw.
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It's a table saw, do you know where your fingers are?

Offline Rchild

  • Posts: 5
The PVC pipes are central vacuum pipes and are extremely light in weight.  We want the overall boom arm to be as light as possible, but yet be just as functional as a commercially available boom arm. the spacers inside the arm where the pipes pass thru are for not only support, but to keep the pipes from rattling and to give the 1/4" outer skin something to attach onto.

Offline martin felder

  • Posts: 103
Bob,

https://woodgears.ca/gear/howto.html

I wanted something that could be made easily in very little time using commercially available parts.  With the gear I purchased online, you drill a hole in the top and bottom plates, index 1 of the gears with a bolt, set the 2nd gear so it meshes, and that tells you where the second hole should be, and you drill there, and you got the right spacing.  When the gears are secured to the arms of the boom arm, the spacing will be correct and it will work.  I would have preferred gears with less and bigger teeth, but bottom line is that the ones I found work.  On the 2 inch OD pipe that is much lighter than PVC, the idea was smooth tubing for the dust collection that was as light as possible to reduce weight.  It just has to be a conduit for dust as it is not what gives the arms strength-rigidity.

Once I get the hose and second set of gears that are being shipped and make a variation of the middle section using wood instead of aluminum in the top-bottom plates and a different bearing approach, I will post these details so anyone can make one easily.  That is the goal.  Of course, I imagine others will have ideas for options that will allow it to be made better or at even less cost.  For gears out of wood, that saves money, but takes a lot more time.  Painting it would make it look nicer than leaving it unfinished, but that takes time.  One could use a bottom pipe or not. The aluminum middle section is strong and looks cool (a lot of credit to Randy) but if I can have the same functionality with some wood substitutions, that would save a bit of money and decrease construction time.

What would just need to be common in all variations is for the boom arm to properly swivel at the mounting bracket, swivel 180 degrees easily in each direction at the articulation, and not twist or sag.  Once I post the parts list and assembly pictures, I am looking forward to see what you all have to say, especially since I am just an average hobby woodworker, and I know many of you are very innovative with way more experience. 

Offline ChuckM

  • Posts: 1840
Getting more excited about this boom arm as more details are coming out. For myself, I'd definitely take the easy way out if I'm to build one, that's using commercially available parts and materials. I kinda like a more turn-key approach for this particular project.

I may build one (probably for a 7 to 8 feet version), and put it aside until I move to a place where I have a higher shop ceiling to use it. Even if I don't get to use it for any reason in the future, the estimated cost seems to be something I can write off without too much agony. :P

For those interested in making or planning to make their own gears, make sure you choose the right wood to allow for wood movement, wear (broken teeth can be fixed but often fail again in time),  etc. I have made a good share of gear parts in the past, and precision is critical for smooth movements and in some cases, long-term use.
« Last Edit: May 25, 2020, 11:40 AM by ChuckM »

Offline Mortiser

  • Posts: 62
Did you consider making the gears from wood? Matthias Wandel has a nice online gear generator app on his web site, or did the last time I visited. You can use it to create templates you can use to make your own gears in any size with as many or as few teeth as you desire (within reason).

Since you are using a box beam type of construction for the arm segments you don't need any structural rigidity in the tubing. There are lighter weight tubes available but not sure if the reduced weight is enough to warrant using them.

Since I live in a rural area every time I go to the dump I watch for someone tossing out an old kids swing set. Some of the pieces will even have well formed bends that could suit dust collection projects. I think that steel tubing used in the construction of those has multiple uses when repurposed. One I have been wanting to build is an overarm dust collection for my table saw.

Bob, as a side note regarding table saw dust collection, have you seen this recent video by Mike Farrington?


Offline martin felder

  • Posts: 103
I mentioned I am waiting on another gear to try a different approach to the bearing of the swivel articulation section that would make construction easier, this is a preview (gear omitted).  In the previously posted pictures with the mid section made of aluminum, Randy seated bearings in the top and bottom aluminum plates.  My thought is to have wider bearings with a larger surface contact area sandwiched between the plates and the arms.  I am really not sure if this will work as well or is better or not than what we know works in the posted example.  When I get the gearsI , I will see.

https://www.amazon.com/dp/B07RV1P6CD?psc=1&ref=ppx_pop_dt_b_asin_title

The above are tapered thrust roller bearings with an OD of 2 inches.  You can get 2 for $12.19 and you need 4. 



In the above picture, I am using a 2 inch OD Forstner bit to drill shallow holes in the top plate.  That can be duplicated on the bottom plate and I was thinking 1 inch or 1 1/4 thick maple (or oak would do).  Then, bore the smaller hole for the bolt using the center marking to insure the smaller through hole is dead center (or keep the wood clamped to the drill press table as you change from Forstner to the smaller bit).



When the bearings are inserted into the shallow hole, the ID of the bearing does not have to be around the size of the bolt. It just has to be no smaller.  Then, with holes for the bolt drilled into the arms, you assemble with washers on the top and bottom, and a lock nut.
Very fast and simple and inexpensive.  One option would be to make shallow wider holes in both the top-bottom plates or arms.  What would make it sag would be the nut coming loose or the wood bending or the bearing failing but one does not have to worry about seating a bearing within metal precisely and I think the wider surface area of this bearing is an advantage.

These are all guesses as I am very much learning as I am going.  I know this is easier than dealing with aluminum and I just want to find out if it will work as well or not.  Doing it this way takes 15 minutes at most and this is the most critical part of the entire project, but it does not matter if it is easy, inexpensive and fast if it sags. 

« Last Edit: May 25, 2020, 12:21 PM by martin felder »

Offline martin felder

  • Posts: 103
FYI, there are 2 people I know of that expressed an interest in making the middle section for now as a one-time project with CNC and metal working machinery and to make it available to others at a very reasonable price as a "one-time tool", like Woodpeckers! 

This entire project was made in a woodshop, but for those who want the most "turnkey" DIY articulating boom arm, it would be by being able to buy the articulating section, and this may be something to consider.  If you are at all interested, with the understanding it may depend on price, please send me a PM as I can gauge the level of interest and forward the information.

To again be clear, I have no financial interest in this directly or indirectly.  I am just mentioning that this may be an option if there is interest since a couple of people may plan to make this middle section. 

Offline Rob Z

  • Posts: 1005
Martin, Randy

Nice work guys! I love to see shop-built stuff on this website.  Like Bob, I would also like to build something like this for the DC over the blade of my table saw.

I'll continue to follow the details as you work on this.

Offline Bob D.

  • Posts: 1687
Darn you @martin felder for that link to the bearings. Now I've gone and bought a couple sets. :-)
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It's a table saw, do you know where your fingers are?

Offline Straightlines

  • Posts: 23
Hey there, neat project Martin & Randy, thanks for sharing!

Question:  I hate to be a dope, but why are the gears needed?

Offline Svar

  • Posts: 2148
Question:  I hate to be a dope, but why are the gears needed?
So it bends symmetrically. There are 3 sections (note short middle section). Without gears it may end up in a Z-shape, will still work but may kink the hose. Gears could be substituted with rubber tires, but those will shift over time.

Offline martin felder

  • Posts: 103
http://shop.sdp-si.com/catalog/product/?id=S12N10M100A0510

https://www.sdp-si.com/ss/pdf/80501061.pdf

The gear used is in the above links, and it worked well on the boom arm that was made where pictures were posted.  I have not yet received another 2 to make a wood mid-section version.  If anyone knows of a better option, please let me know. 

Offline martin felder

  • Posts: 103
I am still waiting on the additional gears so I can see if I can make a middle articulating section more easily and even more inexpensively using wood instead of aluminum for the top and bottom plates.

For an articulating boom arm to work properly, one component is the mounting bracket.  That needs to just be a vertical rod connected to the first arm of the boom arm so the boom arm can swivel at a pivot point.  A hinge can do this, but it has to support the weight of the boom arm.

What was effective and what was used to make the pivot point mounting bracket in the pictured boom arm are the products below:

https://www.grainger.com/product/DAYTON-2-Bolt-Flange-Bearing-with-3FCN4
https://www.speedymetals.com/pc-3951-8210-3-x-3-x-14-angle-a-36-1020-hot-rolled-steel.aspx

If anyone has a suggestion for a better option, please let me know.

As for the 2 arms that carry the dust hose-pipe and electrical cord(s) and perhaps an air hose line, the pipe used was previously posted and within each arm can be just pipe for the vacuum or 2 pipes with 1 for the vacuum and the other for the electrical cord(s).  Detailed plans to follow, but there are some options.

Connecting these 2 pipes in the middle is 2 inch ID hose to fit outside the 2 inch OD pipe (with hose clamps).  I just got 2 different hoses from Air Handling systems (see picture).  The more clear one is extremely flexible and is the perfect choice.  The black one is more stiff but is available at shorter lengths and so I want to see if that will work well because if it does that will reduce cost. 

I was wondering how to connect the boom arm to the Festool vac (eg. CT-36).  I had a hard time finding the answer.   What fits in the vac is something that is around 58mm OD which is around  2.25 inches OD.  What I did was get this:

https://www.oneida-air.com/2-5-inch-static-conductive-vacuum-hose-elbow

It is from Oneida and only costs $10.85.  Notice it says 2.5 inch hose elbow. Well, if you look at the specifications, it says one end is 2.25 OD, perfect for plugging into the Festool Vac, and the other end is 2 inch OD, perfect for standard 2 inch ID hose!

I got it and it worked!  Randy used it on his Fein Vacuum and that worked also (see picture).  That solved the issue of making sure the boom arm would work with Festool vacs.  Just that elbow to flex hose to boom arm.  I was thinking maybe a short piece of flex at the boom arm and vac ends and then maybe some 2 inch pipe in between going up the wall to have less flex hose and a nice way to clamp the pipe to the back wall.  Hmm.

Anyhow, so far, the boom arm that was mounted in Randy's shop has held up very well, and will be connected within 24 hours now that the hose and elbow parts have arrived.  Seems like we were successful in our goal and the followup will be with more specific details. 

In anyone has any constructive criticisms and suggestions for improvement, please let me know. 

 





« Last Edit: May 30, 2020, 11:40 PM by martin felder »

Offline Bob D.

  • Posts: 1687
"If anyone has a suggestion for a better option, please let me know."

Couldn't you use the same components you did for the knuckle in the middle of the arm?

A pair of those bearings with a 1/2" all-thread rod.

For additional support with either method a 1/4" cable stay run from an eyebolt centered over the wall hinge and up a couple feet out to the end of the first segment of the arm. Might create some clearance problems in certain situations but adds a lot of support at low cost.
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It's a table saw, do you know where your fingers are?

Offline martin felder

  • Posts: 103
Thanks for the suggestions.  On the eyebolt-cable, if I understand correctly, it would be like as shown by the yellow line in this picture.



My take on that is that it certainly would add support to the area of the mounting bracket and the first arm at a very low cost and would take 5-10 minutes to install.  That would be an option I will mention when I post detailed plans.  More support is a good thing.

A boom arm can be mounted at any height, but my personal opinion is that the bottom of the boom arm should be around 6ft 8 inches to 7 ft above the floor so (unless you are super tall) so it is well above your head but you can reach up easily to move it without only moving it using the hose coming down.  That means the top of the mounting bracket would be getting close to 8 from the floor.  Adding this support is only possible for those with very high ceilings.   Fortunately, the boom arm we made does not seem to need that additional support to function nicely without sagging and that creates more universal appeal.  Hopefully that will be the case with the even easier to make version I will be working on when I get the new gear.

On the other suggestion, not exactly picturing what is being suggested.  If it is a different option for the mounting bracket, any more details would be helpful.  For what is being used now, we have 2 commercially available parts from Grainger bolted to an angle piece that mounts to the wall with a rod going vertically.  Thanks.

Offline Alan m

  • Posts: 3322
I think if I was building one(or when) . I would make the wall mount plate a lot longer, say 36 inchs  and make the gusset piece on the first arm on the underside . that should add a lot of strength to hold it up and shouldn't be in the way too much
"A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
- Sir Winston Churchill (1874-1965)

Offline martin felder

  • Posts: 103
It is interesting to see the variations in how articulating jib cranes are attached at the mounting plate - initial pivot point.

https://www.ergonomicpartners.com/articulated-jib-cranes#ArticulatingJibsFS

If I understand, you are suggesting something more like the picture on the left below



One thing nice about the mounting bracket in the previously posted picture is that you have the ability to have a longer vertical distance at the pivot point just by using a longer 3/4 inch diameter rod.  The boom arm as is seems to be doing just fine without further support but certainly nothing wrong with more support.  For me, it would be problematic since right below where I plan to mount my boom arm, there are storage cabinets.  However, I do have room above should I want added support using the eye bolt idea. 

One thing that I think helps this boom arm be OK without modification is that it is light.  If only the 1 pipe were used (for vacuum hose), it would be even lighter. 

Thanks!
« Last Edit: May 31, 2020, 07:17 PM by martin felder »

Offline Alan m

  • Posts: 3322
that's exactly what I mean.
if you have the room above then  it is way better to have it up out of the way
"A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
- Sir Winston Churchill (1874-1965)

Offline martin felder

  • Posts: 103
Once I check to see how the alternative mid section swivel option will work out, and then post a step-by-step guide to making one, Randy and I will be sure to indicate how certain things can be modified as options for those with certain preferences.  Another example of that is seen in this picture


The very flexible vacuum hose is seen connecting the 2 pieces of light weigh 2 inch OD pipe (available at Home Depot).  Here you see the pipe below it, but no hose yet installed.  That bottom pipe is to thread the power cord (or 2 cords with 1 plug-it and the other standard extension cord).  The pipe and the bottom hose can house the cord.  However, another option is to have omit the bottom pipe and hose and have the cord travel within the boom arm where it will travel under the top hose.  Another option is to have a small flex hose connected to a very short piece of pipe on each arm (then travel inside the arm) so the cord is covered and protected at the point of articulation, but you save a few dollars on the pipe and a small amount of weight.

Offline Banana

  • Posts: 48
Considering it only needs to support some thin wall pvc and vac hose wouldn't something like this be simpler?


Offline martin felder

  • Posts: 103
https://www.festoolownersgroup.com/festool-jigs-tool-enhancements/another-homemade-boom-arm-63015/

Nice drawing!  For sure that would be more simple and is similar to what was recently posted in a separate thread in response to this thread.  With that design, the maker indicated adding a second articulation was what allowed it to best function.

Interesting that before I pursued upgrading to an articulated boom arm, I could not find one example of a shop made DIY option, and so we incorporated some of the features of the original Festool ASA-5000..

Nice for people to now be aware of options to pick what is best for them, especially if those other very inexpensive DIY options have the same functionality of allowing 8-10 ft extended lengths, no sag, and full articulation.  Are you going to make one like that?



Offline Doug S

  • Posts: 494
It's my homemade boom arm that Martin has linked to.

Regarding the plan that Banana has posted my very first attempt was similar to that, I just used single pieces of 18 mm birch ply for the arms. I found that in use the triangular piece of ply twisted under the weight once the two arms were not in line causing the the arm to sag. I remade it using a torsion box style, some 2" x 1" with a 12 mm birch ply skin over which solved it.

Offline Bob D.

  • Posts: 1687
"On the eyebolt-cable, if I understand correctly, it would be like as shown by the yellow line in this picture."

Yes, your sketch with the cable stay added shows what I am suggesting.
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It's a table saw, do you know where your fingers are?

Offline Banana

  • Posts: 48
Now I understand.  While I appreciated the engineering & rock solidness of Martins box design (hadn’t seen other thread yet) I just couldn’t see past the light weight it had to carry.

The Doug S version has many solutions to issues I hadn’t considered.   

Learning about the ply twist regarding the cheap’n’cheerful mockup I posted (limiting it to only mounting ‘nose down’ as shown),  I wonder if adding significant and equal ballast, on both sides, near the tip of the nose of triangular main arm would stop this?

The only other down'n'dirty approach I’d entertain would be a single longer main arm (of any design) with an under mount track for one or two trolley wheels.  Of course now you get hose draping and hang yourself each time you walk straight into it.  [wink]

Offline martin felder

  • Posts: 103
Boom Arm Version 1 in Randy's shop



That boom arm had a flexible extension cord and air hose, with the air hose now replaced by a plug it.  No sag.  Moves well.  Seems to be functioning perfectly.  However, version 2 will have a few minor changes with Randy thinking of ways to make beneficial tweaks.  For example 1 inch more space on each arm to allow a slightly longer flex hose which may allow cheaper hose to work as well, a bit more distance between the upper and lower pipes to allow more room for the hose and hose clamps etc. 

I now have all of the parts needed to try seeing if I can substitute the aluminum top and bottom plates and use 1 inch thick maple along with the wider thrust bearings to see if we can have the same functionality with easier-faster construction.

Seems to not be a question of it we can make the boom arm or not and have it work well, but if we can make a few changes to make it better, easier to make, and for even less cost.  Plans to follow after that.

Festool USA does not pre-approve the contents of this website nor endorse the application or use of any Festool product in any way other than in the manner described in the Festool Instruction Manual. To reduce the risk of serious injury and/or damage to your Festool product, always read, understand and follow all warnings and instructions in your Festool product's Instruction Manual. Although Festool strives for accuracy in the website material, the website may contain inaccuracies. Festool makes no representations about the accuracy, reliability, completeness or timeliness of the material on this website or about the results to be obtained from using the website. Festool and its affiliates cannot be responsible for improper postings or your reliance on the website's material. Your use of any material contained on this website is entirely at your own risk. The content contained on this site is provided for informational purposes only and does not constitute professional advice.


Offline jdm5

  • Posts: 106
This looks great!  Looking forward to seeing the plans!!!

Thanks so much!
Drank the green Kool-Aid...gave up counting long ago.

Offline ChuckM

  • Posts: 1840
Looks pretty good. Please also provide plywood thickness and tube size if possible fro reference.

Offline martin felder

  • Posts: 103
OK.  Made the articulating section out of wood.   Took very little time.  It ended up looking like this and worked perfectly.

For this, I had the 2 gears and 2 inch OD angled thrust bearings x 4 (links previously posted), two 3/8 hex bolts that were 12 inches long (Ace Hardware), some M10 hex bolts, some fender washers, and some lock nuts for the M10 hex, a couple of aluminum tubes (any narrow pipe will do), some 1 inch maple and some 3/4 plywood. 

So.... first thing was to cut some 1 inch maple - 5.5 x 9 inches x 2 pieces and cut the corners at 45 degrees.  That has nothing do to with function but looks nicer.  If you want it to look even nicer you would do a 3/16 or 1/4 roundover and sand.  I made no effort to make them perfectly identical.  As you can see, if you were to put the gears on top, they would fit

With the gears sitting on top of 1 of the maple pieces mark the center, and drill a hole around 1/4 inch deep with a 2 inch Forstner bit.

Then, keeping the wood clamped to the drill press table, change the bit to a 25/64 or 13/32 bit and drill the hole all the way through.  The center indentation from the Forstner bit is a nice way to know the center also.  This will allow a 10mm bolt to go through.  25/64 is adequate, but you can go 13/32 if too snug. 

This is key.  After you drill the first hole, Take one of the gears and place it as shown and use a drill bit or a 10mm bolt to keep it in place.  Then place the other gear next to is so it meshes.  Then, use a 24/64 or 13/32 brad point bit and insert it through the center bore hole in the gear, and tap it to mark the center.   Then drill the 1/4 inch hole with the Forstner, then drill the other hole through in the center.  If you were to then place bolts through both holes, the gears will mech.   Essentially, you are using the gears to mark the distance between them rather than a ruler. 

Now, on the left you see the 2 Forstner holes and the 10mm or so holes in the middle which are the prefect spacing for the gears to mesh, but we need to duplicate that on the other piece.  So, we put 1 on top of the other, and then use the brad point bit to mark the center.  On the picture on the right, the black arrows show the indentations.   For that piece, you drill the Forstner 2 inch diameter holes and the center holes.

Now, take 4 pieces of 1 inch thick maple 14 inches long and 3 inches wide and mark the center 1 1/2 inches before the end for each piece.  Drill the hole in that marking with the 25/64 or 13/32 bit and round the corners.  The center marking does not have to be perfect.

Now, drill 2 holes for the 3/8 long bolts as shown. Once you do that, then pub the 2 pieces on top of each other and do that same tap with the brad point to mark the corresponding location on the other piece and drill.  Then you assemble as shown on the right.  For this prototype, I used some 3/4 plywood for the arms 6 inches tall and 3 inches wide.  The 4 pieces of 1 inch thick maple were screwed to the arms.  For the undersurface of the top 2 of these, I drilled a hole in the gear and screwed it to the maple with a bolt running through so the gears would be centered. 

For the assembly, on the top, you have the top plate and the bottom plate with the 2 inch OD bearings seated into the wood (courtesy of the hole with the Forstner bit).  Under these plates, you have the extension pieces of maple connected to the boom arms with the gears under the top extensions.  Through the holes you have the 10mm bolts and washers and lock nuts.

I clamped it to the bench and tested it.  Worked perfectly.  I added 20 lb barbell plates to the end.  No deflection.  I lifted it up 7 ft and dropped it on the floor, no damage.  I swiveled it side to side and it never moved on its own but no resistance either.  No wobble or sag.

So far so good.  Again, this is just a preliminary report. I will provide way better detailed plans with more info on exactly how to attach the gears and assemble.  I think the aluminum is the best, but for those who want something more simple, and even less expensive, this seems to be an option that is super easy to make.
« Last Edit: June 07, 2020, 12:36 AM by martin felder »

Offline martin felder

  • Posts: 103
Oh... a couple of people are interested in making a YouTube video going over the instructions step-by-step. 

Offline Svar

  • Posts: 2148
If you want to simplify the design, you can replace gears with straps or cables as shown below (red). Straps attached only at the ends and transition from one curve to another. This principle is widely used for symmetric rotation from children's toys (Jacob's ladder) to industry.



« Last Edit: June 07, 2020, 03:39 AM by Svar »

Offline martin felder

  • Posts: 103
Thanks Svar,

If you have a link to a particular product for straps you recommend as a nice durable option, I can try it.  That would be as easy as unscrewing and removing the gears and adding the straps to see how well it works.  As far as design, I believe it is simple very simple to build with clear detailed instructions and a materials list now that the bugs are worked out.  The gears are just meshed together, and that guides where you drill the holes on the top and bottom plates. That correct spacing is all that is needed to insure the gears work when secured to the boom arm and the center section is assembled.  However, the if straps have identical functionality, and are less expensive, that sounds good!  I already have the gears and it already works, but as I said, I want to see just how easily it can be made at a low cost without compromising functionality and durability.  Therefore, happy to experiment so others can save $ if it works.

Offline Banana

  • Posts: 48
Perhaps a discarded fan belt picked up from a repair shop would suffice to test with?  The composition / lack of stretch / strength / ability to drill through for fastening etc. should exhibit the properties of a similar premium product. 

Offline casper

  • Posts: 19
A great build and good thinking but I am curious why the gears are used? Also did you consider Timken Taper bearings which are adiustable to some extent and having long rollers give more bearing surface area. The one big factor that may be a problem for some is they are not sealed at all. I have built one boom and it was a total failure though it was one piece with no articulation but you have given me ideas on version two. 

Offline Rchild

  • Posts: 5
The gears prevent the extended boom arm from over traveling and keeps them parallel to each other when rotating.

Offline Svar

  • Posts: 2148
A great build and good thinking but I am curious why the gears are used?
So it bends symmetrically. There are 3 sections to accommodate 360 motion. Gears prevent it from bending into Z-shape.

Offline Svar

  • Posts: 2148
Thanks Svar,
If you have a link to a particular product for straps you recommend as a nice durable option, I can try it.
I have nothing specific in mind. Just seemed like another alternative where you could use stuff lying around. As already mentioned drive belt could work well. Also, one strap could go on the lower hinge, the opposite on the upper hinge.

Offline casper

  • Posts: 19
Two observations, you can buy Unbrako bolts that are ground to size and fit with far less clearance in the bearings. Secondly, it occurs to me that if the gear was on top it would be under tension and not compression and this may result in less friction within the gear teeth and the tooth mesh could be adjustable if it was necessary. The mesh clearance could be done after the arm was fully assembled as well. I saw reference to another thread but can't seem to find it.
« Last Edit: June 08, 2020, 12:44 AM by casper »

Offline Bob D.

  • Posts: 1687
Maybe use bicycle chain for the straps. Strong, flexible, and readily available.
« Last Edit: June 08, 2020, 08:27 PM by Bob D. »
-----
It's a table saw, do you know where your fingers are?

Offline Cheese

  • Posts: 7511
Two observations,
1. you can buy Unbrako bolts that are ground to size and fit with far less clearance in the bearings.
2. it occurs to me that if the gear was on top it would be under tension and not compression and this may result in less friction within the gear teeth and the tooth mesh could be adjustable if it was necessary. The mesh clearance could be done after the arm was fully assembled as well. I saw reference to another thread but can't seem to find it.

You're referring to shoulder bolts, that was also one of my previous thoughts for the retention of the bearings.



I agree, any slight sagging of the arm will release pressure on the gears if they are mounted on the top of the arm. If mounted on the bottom, the gears could get jammed up.

Offline Michael Kellough

  • Posts: 4820
I like the straps idea Svar illustrated. Almost anything should work from nylon to neoprene. I’d go with neoprene because if you assemble the joints so the strips are slightly compressed that will also take care of the need to dampen movement.

Offline martin felder

  • Posts: 103
For the shoulder bolts, not sure if that applies to this design (wood version) but I could be mistaken.  On the bearings, I wanted them to be sandwiched between the top plate and the arms on top, and between the bottom plate and the arms on the bottom.  I wanted wide diameter bearings.  I found the 2 inch OD but the center bore was well over what would be used as a bolt.  So, I figured with the Forstner bit, that would seat the bearings, and the hole in the middle would allow the bolt to go through.  If it was not for the gear having a 10mm bore, I could have used 3/8 or 1/2 inch bolts. If a certain shoulder bolt is a good choice, I could try it out if given a link.  I think what helps keep the gears from being compressed or separated is the fact that there is support on top and bottom with a good amount of distance in between.  The bottom line is that what I have now is easy to make and is working perfectly and holding up so far.  I do not know how well it will hold up in 2 years until 2 years from now no matter what I do, but I am trying to stress it, and it is passing.

On these straps, if someone give me a link to a specific product, I am happy to buy it and try it. 

Offline Svar

  • Posts: 2148
Deep groove ball bearings are more appropriate here than thrust bearings. The load on them is mostly radial (through leverage of the arm) rather than axial (downward weight of the arm). Having said that, either one is overkill and will work fine.

Offline Michael Kellough

  • Posts: 4820
Changing my mind about using simple neoprene, reinforced flat belting would be better.

The McMaster page

Smaller width belts are the same cost. If you need two 3/8” belts you could buy one at 3/4” and rip it in two. You order by circumference so just get one belt a couple inches longer than the radius X2 for each side of the knuckle and then cut the belt in two equal parts. That’s two belts, or one that’s twice as long and cut it into four equal lengths.

Also, rather than reworking the spacing of the holes in the parts to try and compress the belting (to get some resistance to motion so the arm stays were you park it) and following Svar’s comments about any kind of (low friction) ball bearing being overkill, you could simplify drilling and reduce cost by using bronze bushings or steel sleeves. A little friction is good and the arm gives you plenty of leverage to easily overcome it.

McMaster page of 1/2” bore press fit drill bushings

I’d use ordinary nominal 1/2” bolts with these (usually a little smaller than the nominal size). Precision shoulder bolts will require precise drilling and pressing on bushings.

Another option is bronze bearings. Use ordinary bolts with these too.

McMaster page for DRY bronze bearings for 1/2” shaft

These won’t stain the wood. I’d use the largest od bearings so there is less wedge force on the wood. I’m a little nervous about the change to wood. If the wood holding a bearing splits the arm could fall? You could make it safe by running a bolt side to side through the wood.

Offline Rchild

  • Posts: 5
The way I have the bearing on the boom arm I made, seems to work perfectly.  I drilled and reamed out a hole to fit the 26mm bearing and pressed the bearing in..that bearing is NOT coming out at all unless driven out. With the boom arm that MartinFelder is making, the bearing is seated in the slot he drilled using the forestner bit.  It's not moving either and it works very well for what he is doing.  As for using straps instead of gears, what is to keep the strap from slipping off the rounded plate when rotated (since that plate is only 5/16" thick aluminum or..3/4" lumber if that's what is used) when slack on the strap is present? Perhaps some sort of "Lip" on the top and bottom plates?  The gear really does work well in keeping the arms aligned and was not hard to secure onto the plates. 

Offline Michael Kellough

  • Posts: 4820
Glad to hear it’s working well as is. What I posted might be better suited for another forum where the economy version is desired.

Offline Rchild

  • Posts: 5
What you posted is great..it gives more alternative ways to make this boom arm..all ideas are welcomed and encouraged.. I don't know everything..I can only attest to what I did for my boom arm..but I would love to hear better and easier ideas

Hei,

Very interesting development!

How about if you replace the gears with pieces of bicycle chain?
- fixed from both ends, and if falling down you could add nails or similar that gets on the slots in the chain.

BR. Simo

Offline martin felder

  • Posts: 103
As an update, the first boom arm was mounted to the bracket with a 6 inch long  3/4 diameter hole drilled through wood.  That worked out great.  On the next boom arm, it was not plumb.  The drill bit used was not long enough to go all the way through with 1 pass from 1 direction.  I figured that could be a problem for others.

So, modification using flange bushings



With this, you can use Forstner bits to drill accurately a short distance into the wood from both directions and have a larger hole in between so the rod is secured top and bottom.

Anyhow, getting close to final plans.  The boom arm works, but wanting to get a few things dialed in for upgrades that will make construction easier.

Offline martin felder

  • Posts: 103
Picture of the current mounting bracket



Picture of the boom arm mounted



In the picture of the mounted boom arm, it was taken as I was passing the power cords (1 plug-it and 1 standard).  It is fully functional with the wood version of the center pivot point.  Some day I will swap it out for an aluminum version.  It works and it is great having a working articulating boom arm in my shop.

My plan was to post a detailed guide at this point.  However, a couple of things I want to first upgrade.  On the mounting bracket, there is just a little bit of sag.  That would be remedies by shimming out the bottom bolts, but still a bit of sag when to the side.  That is not present on my friend Randy's boom arm and I am wanting something just right if I am going to suggest it to others.

Another imperfection is there is just a slight twist of the first section of the boom arm with the second arm off to the side, and I am thinking the first arm could be made a bit beefier, with care being taken not to add too much weight.  Along with that, I could have the first arm be a bit taller at the area of the mounting bracket to have a longer rod as was mentioned.

I would be curious if someone has a link to what may be a better option for a mounting bracket.