Author Topic: Air Sander for Gelcoat Stripping  (Read 8144 times)

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Offline SaltyDog

  • Posts: 8
Air Sander for Gelcoat Stripping
« on: January 28, 2007, 10:46 PM »
I have a large project (40 sailboat) that needs the gelcoat stripped on deck and then separately from the waterline to the toe rail.
What is the advantage of an Air sander vs electric ? other than 1.1 lbs I am not sure I am seeing any.

S

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Offline Barry

  • Posts: 55
Re: Air Sander for Gelcoat Stripping
« Reply #1 on: January 28, 2007, 11:06 PM »
My understanding is durability.  Air sanders have fewer things inside of them to break.  For that much work the sander will be running flat out for quite some time.  A regular electric sander will generate much heat  in use, and shorten the life of the sander as a result.  The air sander doesn't suffer from this, that whole moving air and cooling effect thing.

If I had the much work to do, I would get the air sander.
Central NJ

Offline Bob Marino

  • Posts: 3212
Re: Air Sander for Gelcoat Stripping
« Reply #2 on: January 28, 2007, 11:09 PM »
First thought, If you are referring to Festool's air sanders, I would think the larger pad (7")and 9/32" sanding stroke would be quicker than their electric cousins. One hose for air, dc and exhaust, makes it more mobile. Less moving parts also extend the life of the sander.

Bob
Former Festool  Dealer since 2002; user well before that!

Offline Jim Dailey

  • Posts: 278
Re: Air Sander for Gelcoat Stripping
« Reply #3 on: January 29, 2007, 12:32 AM »
SaltyDog,

If I am understanding what you are proposing.... the shear scope of the project exhausts me thinking about it....    For those unfamiliar with what he is saying he needs to do... the amount of work would be like taking off every piece of trim and refinishing a city block of "pill hill victorian houses...."  :o

I think air sanders would be great if you have a very large 2 stage compressor.  Dust collection is a huge issue, in this case you are the canary.... like miners in a cave it's not good for the canary to wilt!!!  The dust you will be creating is toxic, an environmental hazard, a fire hazard and a health hazard to you.  Good dust collection is very important & something the marina will require because of PCA if it's on their property.   The dust collection of the Festool sanders that Bob mentioned would be excellent if you have a compressor with the CFM to run them. If not the durablity & low vibrations of the Festool electics will pay dividends as you holding them above your head.   You should also think very seriously even with the Festool sanders about a powered respirator drawing fresh air from up wind of the project.

Additional sanders that I would recommend, are the RAS 115 E rotary & DX 93 E.  The RAS 115 E can remove gel-coat in the blink of a eye.... but the damage this can also do in unskilled hands is frightening!

Hopefully this will be done indoor out of the weather... but if you are going to attempt this in the great outdoors....  water will be your enemy 'cause this will take on water like sponge, particularly if sections of the core are exposed like the deck.  Time is of great importance on getting this sealed up quickly....  the right combination of tools & skills is very important to shorten the time & work evolved.

As mammoth as this project you are proposing in the "removal" that's the easy part.... re-skinning this will be even a larger project.  And the quality of the finished product will drastically effect the value of the boat.   Larger sanders with their larger surfaces will be better for leveling/smoothing epoxy filled surfaces; like the 7" sander Bob mentioned, or RS 2 E or RO 150.  The LS 1300 with it's concave & convex profile would also be invaluable.  The correct grit of paper for leveling of the fillers with good dust collection will make your like much easier.  I really like the Festool Brilliant paper but suggest you talk to Bob Marino about the new Crystal paper.

I'm not trying to scare you.... But the reality of a project like this will "hit" you with a deep sinking feeling a point not long after you started.... when you realize you are committed to the point that you can't go back....  a you realize on how much is if front of you....   I know 'cause I'm stupid enough to work (love) on boats.

Best of luck my friend, best of luck,
jim
Life is just a series of projects...

Offline SaltyDog

  • Posts: 8
Re: Air Sander for Gelcoat Stripping
« Reply #4 on: January 29, 2007, 09:18 AM »
Thanks for the comments:
"Lioness" is a 1962 Bermuda 40, and lets just say that for those who don't know, Hinckley yachts,  her builder's set a standard of workmanship that is hard to match, but I can't afford to let them have her back to do the job at something over $30k from last quote in 2004.

I do realize the scope of that which I am contemplating, and I do comprehend the toxicity (have sprayed my own Awlgrip etc). The work site is next to my garage, and I will enclose with a poly tent in April, trying to hit the balance of cool weather to "comfortably" wear a Tyvek bunny suit and respirator and then shortly thereafter warm enough to spray the 545 primer and use the Awl fair (http://www.awlgrip.com/awlgrip_pages/datasheets_pds_new.htm) both of which are temperature sensitive and still get in a good sailing season.

I do have a Rotex 125, one of the  RO 125, the linear and detail sanders as well, along with a CT-mini vacuum,  they did a great job on the teak and refinishing the bottom last season. During that project, the duty cycle was limited by my ability to work overhead and at arms length, so I was not as worried about continuous use as I fatigued often and needed a break. My girlfriend has/will be helping, so a tool that does not exceed her hand/arm strength was also a factor in selecting the 125 vs 150.

This year's prospective project would be working at waist level from staging so I would not be the limit. I am looking at the Air sanders along with a Hutchins (http://www.hutchinsmfg.com/) linear sanders and marine rasp for the fairing and am prepared to buy a 12 cfm@90psi  compressor to run it.
Since the weather window of > 55F to cure the fairing compound means I will be working in May in New Hampshire, I am thinking about starting to strip in April, and with solar gain and propane heaters be able to cure the primer and fairing compound. I have used the system before, so I do have appreciation for the temperature effects etc.


Offline Jim Dailey

  • Posts: 278
Re: Air Sander for Gelcoat Stripping
« Reply #5 on: January 29, 2007, 12:08 PM »
SaltyDog,

The lines of a Hinckley Bermuda 40 are every bit as classic as the most stately Victorian mansion.  For most Bermuda 40 is what a "yacht" should look like....  and well worth your time & effort.

Tackling the bottom on a 40'  boat was no small project.  You've got to love a women that will help on such a labor intensive project.  My girl friend not only sands teak but looks good in a bikini doing it!!!  We had quit a crowd checking out the stack of Systainers, Festool sanders & the CT 22 we used our boat last summer...  I'm sure that's what all those guys where checking out....

You may also consider a gelcoat planer.  I can't say I've used one, but one name comes to mind "Marine Shaver 800-932-5872  Although I have seen a guy go at the bottom of a boat with a power planer for wood like the Festool HL 850 E , however the damage he did to the hull was significant....  many gouges, but worst yet he didn't properly fill & level the gouges.   You should also have ear protection because of the very high db level of these devices.

Axis Products makes a positive flow respirator w/40' of hose & a full face mask for about $500.  I have their 4 stage HVLP the Citation model that has the same respirator built in.   I use this a lot.  You can do a Google to find their website.

Hutchins does make the right equipment for the job but even at 12 cfm@90 psi that compressor will be working very hard, possibly not stop to keep up.  I hear people say to take the specs like the marine air rasp at 11.4 cfm & double the cfm's to get a properly sized compressor.  I have a 2 stage compressor with about exactly the same specs & I'm always running out of air..... and.... waiting..... for .... it.... to.... catch..... up.....

You are so right about the temperature range.... 50 degrees is the magic min #,  but the hull act's like a big heat sink...  in the spring I figure I prep all day to put one coat of material on in the mid to late afternoon.  Summer you can get multiple coats, but too high of temperature, humidity & bugs can all give you problems.

Hope this helps, jim
Life is just a series of projects...

Offline SaltyDog

  • Posts: 8
Re: Air Sander for Gelcoat Stripping
« Reply #6 on: January 31, 2007, 09:21 AM »
Good input on the compressor sizing, that sort of tips the decision to the two stage 80 gal vs 1 stage 60 with similar cfm ratings.

 I had the bottom professionally planed back in 2000, but the deck would seem to be harder due to the odd corners and the cabin house thought this tool you referenced http://www.paintshaver.com/marineshaver.html would seem to be nimble enough to get around that, and its clearly FAST and CLEAN

I would still need to do the "long board" fairing, but that may be solved with a 1/2 sheet sander or a smaller air file driving an attached batten to get a 24" span.

Offline Jim Dailey

  • Posts: 278
Re: Air Sander for Gelcoat Stripping
« Reply #7 on: January 31, 2007, 11:09 AM »
SaltyDog,

Thanks for the link on the Marine Shaver.  That's exactly what I was talking about. 

The key to keeping things fair, is keep moving!!!  If you watch me sanding you'll see my shoulders are getting a work out.  The other is "feel the work" with your hands & use side lighting to show the high/low spots.

You are right about the 80 vs the 60 gal tank, more is certainly better here.  The problem is all the makers of compressors lie as a matter of course in stating their CFM.  I'd suggest doing a search on Woodnet, this was a topic covered maybe a year ago.  Or repost a question about stated cfm vs real cfm.  Several of the people who posted responses where very knowledgeable in this area.

To quote the great Red Green.... "we're all in this together..."

jim
Life is just a series of projects...

Offline SaltyDog

  • Posts: 8
Re: Air Sander for Gelcoat Stripping
« Reply #8 on: January 31, 2007, 02:50 PM »
Doing a bit more research...

I have a recommendation from Hutchins on a few tools,

Quote
The retail pricing for the models you requested are:
Model 4906 $396.85 (low speed high torque vacuum assisted grinder)
Model 3970H $313.75 (includes hookit pad) (finishing vacuum assisted DA or ROS sander)
Model 3806 $467.72 (8x18 INCH orbital sander for BIG areas)
Pad # 5028H (8" Hookit Vacuum Pad) $32.60
They would require a $1000 range compressor to crank out 10-15cfm at 100psi.

I am looking back at the Festool Planer as a logical alternative to the other purpose built gelcoat machines such as the marine shaver and the gelplane from the UK, which was on ebay for $2k.


It looks as though that ought to be able to do what I want, and its "only" $450" or so, compared with $700 for the shaver and much more for the other Pneumatics.

Regarding your advice, I keep moving the sanders to the point that in doing the bottom and last season's find sanding of the hull I ended up with "Popeye forearms", but as you know, working on a deck and cabin there are few really flat sections, and its bloody hard to "keep you ass behind you" as I learned from the Hinckley Yacht's electrician (in other words, get in position to work without odd body contortions etc) when you are working off a ladder, staging or on the surface you are standing/kneeling/sitting on. At least she won't be pitching in the chop at the mooring/dock.

(having sanded and varnished from a dinghy along side)

S





Offline SaltyDog

  • Posts: 8
Re: Air Sander for Gelcoat Stripping
« Reply #9 on: February 02, 2007, 08:40 AM »
Just a wrap up, I made a call to the builder, who recommended getting a Milwaukee 9" grinder and using 60 grit.

' we don't use them fancy tools, just get out there and make it happen.' all in a Maine accent.

So I will try my Rotex and see how it goes,

Offline Jim Dailey

  • Posts: 278
Re: Air Sander for Gelcoat Stripping
« Reply #10 on: February 02, 2007, 08:56 AM »
SaltyDog,

Less is more....

I have seen some very serious damage done with a 9" grinder!!!!   

I think the Rotex is the better call.

jim
Life is just a series of projects...

Offline Dave Ronyak

  • Posts: 2234
  • Flyin' from NE Ohio
Re: Air Sander for Gelcoat Stripping
« Reply #11 on: February 02, 2007, 02:28 PM »
Just a wrap up, I made a call to the builder, who recommended getting a Milwaukee 9" grinder and using 60 grit.

' we don't use them fancy tools, just get out there and make it happen.' all in a Maine accent.

So I will try my Rotex and see how it goes,

I hope you have strong arms and excellent hand/eye coordination if you go that route.  You could definitely achieve a high material removal rate.  A couple of years ago I used a 7" angle grinder with 36 grit aluminum/zirconia abrasive disks to carve down the very uneven tops of 2 X joists on a 15' X 30' deck to match the elevation.  I removed at least 1/2" from most of themt to level them relative to another pre-existing decking section.  The whole process only took about one hour - most of which was checking my progress with some string lines.  Try the RO 150 first.
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