Author Topic: Third-party Longer Mortise Bit for DF500 (Read 11702 times)

ChuckM · « **on:** August 18, 2016, 04:56 PM »

DF700 users can buy third-party cutters and use the 700 like a DF500. Is there anyone out there producing and selling longer cutters that we can use a DF500 with longer Dominoes like the 8mm x 22mm x 80mm, or even the 100mm?

Please share the source if anyone knows about such cutters for DF500. Thanks.

Chuck

Birdhunter · « **Reply #1 on:** August 18, 2016, 06:03 PM »

I would think putting a longer bigger cutter on the 500 could add more stress on the machine than what it was designed to handle. The adaptor for the 700 allows a smaller cutter to be used so the stresses would be lower.

ear3 · « **Reply #2 on:** August 18, 2016, 06:12 PM »

I'd have to double check the machine, but I imagine there are physical limits imposed by how close to the front the arbor is. In resting position, the standard bits are already near the mouth, so any longer and they would be poking out even without plunging.

ChuckM · « **Reply #3 on:** August 18, 2016, 06:23 PM »

Good point about the depth of the mouth.

I was thinking of a longer cutter used with the narrow (standard) setting for occasional projects. Recently, I completed a joinery by setting the max. of depth of cut and using 80mm cut to 56 or 57 mm long Dominos (5mm longer than the standard 50mm pieces, not much). But if we could use a cutter that mortises 65 mm or even 70mm, it would sure help.

May be I could attach a spacer at the front of the plate to keep the cutter from protruding?

I can't justify getting a DF700 and I also find it an over-kill for most of my projects.

Chuck

PS If I were doing just a joint or two, I could drill the mortises longer and use the 80mm Dominoes in their entire length. Too much work for regular joinery, though.

Svar · « **Reply #4 on:** August 18, 2016, 06:33 PM »

What is the maximum plunge amplitude (travel) on DF500? You can't cut deeper than that unless you do it with shorter cutter, replace the cuter with longer one and deepen the hole. Or am I missing something? Alternatively, install long cutter and place a spacer between the fence and the stock, cut, remove spacer, cut deeper into the same hole. Which pretty much defeats the purpose of this quick and accurate machine.

Michael Kellough · « **Reply #5 on:** August 18, 2016, 07:00 PM »

Svar is right.

If you could get longer bits for the 500 you couldn't use them
unless you replaced the posts (that the machine slides on) with longer posts.

However much longer the bit is, you have to back up that amount, unless you've already made a mortise in that location.

ChuckM · « **Reply #6 on:** August 18, 2016, 07:19 PM »

Quote from: Svar on August 18, 2016, 06:33 PM

Alternatively, install long cutter and place a spacer between the fence and the stock, cut, remove spacer, cut deeper into the same hole. Which pretty much defeats the purpose of this quick and accurate machine.

I agree that method would undermine the speed and accuracy, which, even if the longer cutter were available, I wouldn't use in my day-to-day cuts. But that option would solve the occasional joinery needs that can only be met by a DF700. And it would still be faster and more accurate than drilling a series of holes inside the mortises.

Chuck

Svar · « **Reply #7 on:** August 18, 2016, 07:25 PM »

Quote from: ChuckM on August 18, 2016, 07:19 PM

Quote from: Svar on August 18, 2016, 06:33 PM
Alternatively, install long cutter and place a spacer between the fence and the stock, cut, remove spacer, cut deeper into the same hole. Which pretty much defeats the purpose of this quick and accurate machine.

I agree that method would undermine the speed and accuracy, which, even if the longer cutter were available, I wouldn't use in my day-to-day cuts. But that option would solve the occasional joinery needs that can only be met by a DF700. And it would still be faster and more accurate than drilling a series of holes inside the mortises.

Chuck

Actually you are right. This might not be too bad if the spacer is not just a piece of scrap, but well designed jig with reference marks and pins, etc.

Bohdan · « **Reply #8 on:** August 18, 2016, 08:53 PM »

A longer cutter would also give a wider cut. On a wide setting this could result in the cutter internally hitting the sides of the machine. You would also need to make custom length and width dominoes to utilize any benifit.

greg mann · « **Reply #9 on:** August 18, 2016, 09:38 PM »

What is gained by going deeper? The joints will most likely already fail by the adjoining wood coming apart, not the domino letting loose. Alternately, if you get more strength through depth, the wood holds and puts all stress on the domino, does it fail because it needs more cross-section? Seems like this is why the 700 was designed for bigger dominoes.

Rough analogy: If you put a fence post 2 feet deep and it will break at ground level when subjected to stress, what is gained by sinking it 3 feet?

Mort · « **Reply #10 on:** August 19, 2016, 12:22 AM »

If you only bury that fence post 6" it's going to tip over.

I'd like to have a deeper one for making extra wide mortises, and home made tenons.

bobfog · « **Reply #11 on:** August 19, 2016, 10:01 AM »

The short answer here is if you can afford it, people need both the 700 and 500 if they want all their bases covered through the use of dominos. No matter how many adapters or third party gizmos you have none are a true replacement for having both machines.

I wonder if Festool will ever bring out a Domino XXL?

rvieceli · « **Reply #12 on:** August 19, 2016, 10:19 AM »

@bobfog

They already have one.

https://www.festool.com/Products/Pages/Product-Detail.aspx?pid=769536

bdiemer · « **Reply #13 on:** August 19, 2016, 01:28 PM »

It's just bad math to extend the domain of any machine. I should know, I'm bad in math.

ChuckM · « **Reply #14 on:** August 19, 2016, 08:13 PM »

I was thinking that if someone could come up with an after-market set of cutters for DF700 to be used as a DF500 (that actually did extend the domain of the DF700), may be something could be done to benefit the DF500 users.

I mentioned about using only the standard setting with a longer cutter. Why deeper? To add strength to a joint, for the same reason why Festool has the 8 x 22 x 80 mm & 100 mm Dominos.

In a recent project, with the DF 500, I cut my mortises to the max. (57 or 58mm?) and then cut a batch of 80mm Dominos to an hair shorter than 58mm. I then drilled a deep hole into each mortise for the excess glue. Did 8mm longer matter? I don't know but that was all I could do -- unless I borrow a DF700 from a buddy (that would have quite delayed my project).

I knew owning a pair of the DF500 & 700 would be the best option, but I would not use the DF700 enough to justify it, as a hobbyist. Between the two, I would prefer to have DF500 for its ease of handling.

The making of custom Dominos is my least concern even if I don't want to modify Festool stock (probably the 80mm or 100mm ones). I can cut floating tenons of any size and length with ease in my shop.

May be someone could study this in depth and explore if it is technically feasible to extend the capability of the DF 500 a bit. Yes, on the surface, it is un-doable, just like many other inventions -- the SawStop is an example until it came to the market.

Chuck

greg mann · « **Reply #15 on:** August 19, 2016, 09:23 PM »

Quote from: Mort on August 19, 2016, 12:22 AM

If you only bury that fence post 6" it's going to tip over.

I'd like to have a deeper one for making extra wide mortises, and home made tenons.

You are turning my example upside down to argue against a point I did not make. Where did I imply going shallower was even part of the equation?

Mort · « **Reply #16 on:** August 19, 2016, 10:39 PM »

Easy there, bro-tato chip.

With a longer tenon the force of stress on a joint would be distributed on a longer area.

Your fence post analogy implies that it doesn't matter how far in you sink it as long as it sinks. If you sink that post in 3 feet you have another foot of material holding it laterally. Stability is this enhanced. If you go shallower, stability decreases. Simple physics.

Bohdan · « **Reply #17 on:** August 19, 2016, 10:50 PM »

I think that the real question is, if you break the joint, exactly what breaks.

Will it be the domino or will it be the surounding wood. If the domino breaks then a deeper one would have made no difference. If the surrounding wood breaks then a deeper domino may have helped but if the domino pulls out then maybe you didn't use enough glue or it wasn't long enough.

Has anybody seen any tests that tested domino joints to destruction.

greg mann · « **Reply #18 on:** August 19, 2016, 10:53 PM »

Quote from: Mort on August 19, 2016, 10:39 PM

Easy there, bro-tato chip.

With a longer tenon the force of stress on a joint would be distributed on a longer area.

Your fence post analogy implies that it doesn't matter how far in you sink it as long as it sinks. If you sink that post in 3 feet you have another foot of material holding it laterally. Stability is this enhanced. If you go shallower, stability decreases. Simple physics.

You missed my point. If there is only so much inherent strength in the mortise (or post) sinking it deeper will not help. In my analogy I pointed out If the post snaps off at 2 feet sinking it to 3 feet won't help. Raising it to 6 inches will save the post but there will be a different failure, of course. I never advocated shallower mortises. I just pointed out deeper won't make it stronger if you surpass the inherent strength of the domino.

greg mann · « **Reply #19 on:** August 19, 2016, 11:01 PM »

Quote from: Bohdan on August 19, 2016, 10:50 PM

I think that the real question is, if you break the joint, exactly what breaks.

Will it be the domino or will it be the surounding wood. If the domino breaks then a deeper one would have made no difference. If the surrounding wood breaks then a deeper domino may have helped but if the domino pulls out then maybe you didn't use enough glue or it wasn't long enough.

Has anybody seen any tests that tested domino joints to destruction.

My point, said more elegantly.

ChuckM · « **Reply #20 on:** August 19, 2016, 11:03 PM »

Quote from: Bohdan on August 19, 2016, 10:50 PM

I think that the real question is, if you break the joint, exactly what breaks.

Will it be the domino or will it be the surounding wood. If the domino breaks then a deeper one would have made no difference. If the surrounding wood breaks then a deeper domino may have helped but if the domino pulls out then maybe you didn't use enough glue or it wasn't long enough.

Has anybody seen any tests that tested domino joints to destruction.

This? http://www.finewoodworking.com/item/7592/readers-respond-to-our-joinery-shoot-out

JimD · « **Reply #21 on:** August 27, 2016, 07:08 PM »

I don't remember seeing the FWW test result but the video suggests it is similar to the Wood test. Their tests stressed the joints the same so they should get similar results. That test is representative of the back leg to the seat support joint as the video shows. At least it is when somebody leans back. But that isn't the only type of stress the chair sees. It may well be the peak stress, however. The conclusion is that a lap joint is the strongest, mortise and tenons are strongest when the tenon is 1/2 the wood thickness (not the more typical 1/3), biscuits not very strong, etc.. Dominos did not fare well in the Wood test but that was at least partially because they used a much smaller joint than the traditional mortise and tenon joints. Surface area of the joint makes a significant difference, in other words. Same reason the lap joint was strongest.

If you only occasionally need bigger mortise and tenon joints you could cut them more traditional ways. They are much slower but work well. I use a benchtop hollow chisel mortiser, for instance, that will cut joints about 3 inches deep and as wide as you want (it's maximum chisels are 1/2 inch but you can cut overlapping holes easily). It costs around $250 - much cheaper than Dominos. Even cheaper is to just drill and chisel. But a benchtop mortiser is much faster than drilling and chiseling - but much slower than using a Domino.

threesixright · « **Reply #22 on:** February 18, 2019, 05:25 AM »

OK, probably stupid thought, but here it is:

Any change you could use the DF 500 and for those (rare) occasion you need bigger tenons, deepen/widen the mortise with a OF1400 (has also max. depth of 70mm) ?

RussellS · « **Reply #23 on:** February 18, 2019, 01:00 PM »

Quote from: threesixright on February 18, 2019, 05:25 AM

Any chance you could use the DF 500 and for those (rare) occasion you need bigger tenons, deepen/widen the mortise with a OF1400 (has also max. depth of 70mm)?

Yes this would be possible. Using a router and/or drill press, you could increase the depth of the mortise. The Domino 500 drills 28mm deep maximum. Lets round that to 30 and 60mm total Domino length. For the Domino 700 Festool sells 80 and 100mm length Dominoes. So you would need to drill/rout an extra 10 or 20 mm of depth on each side of the mortise. Aligning the router or the drill press would not be easy, but could be done. I am sure you can buy 8 and 10 mm drill bits and router bits that are long enough to go 40 or 50mm deep in each mortise. I'm sure Europe has them. You might have a little problem with aligning everything so the extra 10 or 20 mm depth you drill/rout may not be perfectly aligned and smooth with the original Domino mortise. So likely you would need some Epoxy filler for the last 10 or 20 mm of the Domino to take up the excess space and looseness. Since Epoxy is strong and hardens when dry, I don't think this excess space would affect the overall strength of the joint. And you would get the full benefit of the 80 or 100mm long Dominoes in the 8 and 10mm size.

Now whether this deepening makes sense, I don't know. Lot of extra work for likely minimal if any extra benefit, strength. Probably better to just add a couple extra 50mm long Dominoes to each joint and not worry about going deeper. Just go with more tenons, not deeper tenons.

threesixright · « **Reply #24 on:** February 19, 2019, 05:07 AM »

Quote from: RussellS on February 18, 2019, 01:00 PM

Quote from: threesixright on February 18, 2019, 05:25 AM
Any chance you could use the DF 500 and for those (rare) occasion you need bigger tenons, deepen/widen the mortise with a OF1400 (has also max. depth of 70mm)?

Now whether this deepening makes sense, I don't know. Lot of extra work for likely minimal if any extra benefit, strength. Probably better to just add a couple extra 50mm long Dominoes to each joint and not worry about going deeper. Just go with more tenons, not deeper tenons.

Thanks Russel, thats bring up a interesting point, which is: I would assume a longer tenon would given a lot more strength, then more tenons? I don't know the math behind it, but instinctive. I would rather choose a few longer ones.

Are there any 'rules-of-tumb' when it comes to the thickness and length of these tenons?

ChuckM · « **Reply #25 on:** February 19, 2019, 11:46 AM »

Widening or making the mortises thicker is not an issue with the DF500 joiner. You simply make the first cut as usual and then reposiiton the joiner (without changing any other settings) against the same reference surface to do a second cut to widen the mortise. To make it thicker, adjust the fence (higher or lower) -- and again keeping all other settings unchanged) -- and cut again.

I am not giving up, and am still hoping someone might come up with either a commercial or homemade solution that can mill mortises deeper with the DF500 joiner. Hey, even someone has come up with a prototype that can address the kickback problem with a circular saw, that I am sure few ever thought of.

RussellS · « **Reply #26 on:** February 19, 2019, 12:55 PM »

Quote from: threesixright on February 19, 2019, 05:07 AM

I would assume a longer tenon would give a lot more strength than more tenons? I don't know the math behind it, but instinctive. I would rather choose a few longer ones.
Are there any 'rules-of-tumb' when it comes to the thickness and length of these tenons?

I am sure there are engineers who deal with foundations on buildings and houses who have the math to determine the optimal number and depth of foundations (tenons). I believe on the Gulf coast in Miss. and Lou. they build houses on marshy soft ground by driving poles into the ground to establish a foundation for the house. I suspect these people could tell you whether its better to drive six poles 40 feet deep or twelve poles 20 feet deep. But I'm guessing it may be like someone wrote at the beginning of this thread. If a post driven 2 feet into the ground is unmovable, unbreakable, then what is gained by driving it 3 feet into the ground? If its 100% perfectly strong enough, then no need to waste effort making it stronger.

For rules of thumb about Dominoes, I assume they are the same as mortise and tenon, slip tenons, loose tenons. The old 1/3 scale for thickness. 1.5" thick leg, make the tenon 0.5" thick. Roughly, give or take. I prefer thicker tenons personally. As for length and width, kind of the longer and wider is better theory. Within some logical restraints. Unless you carry things to wacky extremes, just making things so they look right will be perfectly good.