CMT Domino cutters

[mat]

Used the 14mm CMT cutter and found the stock domino loose tenon to be sloppy. It is 14mm and indeed cuts a 14mm mortise but when I check the Festool cutter and mortise it is actually slightly under 14mm.
OK for user made tenons but not for domino stock.
Mat

 

[JimD]

I like my CMT cutters but have been a bit concerned about reports of over size mortises with them.  I don't plan to buy domino tenons but would like to have that option if a project requires a bunch of the same size tenons.  So today, I went out and measured my cutters and, crudely, some mortises.

I used dial calipers I keep in the shop that are imperial, not metric.  They read in fractions of an inch or decimal inches.  So I converted to metric using 25.4mm to the inch.  For mortise size, I did not try the calipers but might be able to use them for the largest ones.  What I did was use a large set of drill bits with letter and number size as well as fractional inch size bits to test the mortises in a sample block I made after getting my XL.  It is a cut off from a newel post and is laminated oak (3 layer I think).  That worked best for the 5mm mortise where there were lots of bits about that size but gave some idea through the 12mm mortises made with a festool bit.  My 5mm, 8mm, 10mm, and 14mm cutters are all CMT.

I measured the 5mm at .195 inches or 4.953mm.  a #7 drill bit was snug in the mortise, it is .201 inches or 5.105mm.

I measured the 8mm at .311 inches or 7.899mm.  My .316 inch drill bit was tight, that is 8.026mm.

I measured the 10mm at .392 inches or 9.957mm.  A .397 inch drill bit (10.08mm) was snug.  .4063 (10.32) wouldn't go.

I measured the 12mm at .472 inches or 11.98mm.  A 15/32 bit, .4688 inches or 11.90mm was loose.

I measured the 14mm at .55 inches or 13.97mm.  I have no twist drills close to this.

My calipers only read to .01 inch so the last digit is an estimate.  I could easily be off .001 inches or .025mm.  the drill bits could also be a little off.

So this is somewhat crude but I do not see in my bits a reason to be concerned with Festool tenons fitting.  I also measured the thickness of a festool tenon.  I got .478 for a 12mm, the only size I have.  My home made tenons are about .47 thick and fit fine - snugly - in the 12mm festool cutter made mortises.  .478 is a little more than 12mm but the outside is stamped and they go in fine with light taps of a deadblow.  If smaller size festool tenons are also ~.1mm over their stated thickness the 5mm would be snug in my 5mm CMT cutters mortises. Even if there is .1mm play, they would work fine.  My 12mm tenons have been exposed to the atmosphere for months which may have added the .1mm.

 

[Mike Goetzke]

I was also curious since I have a few CMT bits that seemed to be giving slightly loose tenons but not enough for me to worry about. I looked into this a bit and found I must have started to bore the slots too fast. I slowed down a little and tenons are tight again. I mostly use oak and the difference in change in speed was actual audible. Too fast sounded a little choppy and slower very smooth.

Mike

 

[ChuckM]

The majority of users I have observed in person regardless of their experience with the DF make their plunges too fast. You can easily tell from the "chatter" sound they make. Some YouTubers show the same behavior. May be that's the way they have used their routers?

 

[HarveyWildes]

The majority of users I have observed in person regardless of their experience with the DF make their plunges too fast. You can easily tell from the "chatter" sound they make. Some YouTubers show the same behavior. May be that's the way they have used their routers?

I did a major slowdown in plunging since I damaged the bottom plate of the Domino 500 body (not the fence) when I was plunging quickly and the cutter caught in the wood, torqued the wood, and did something weird internally to the tool.  Festool fixed it, but I've been very careful to hold both the work piece and the tool securely, and to plunge slowly ever since.

I've not heard of anyone else that has had that problem, so I think it was a combination of factors.  After paying more attention to the sound of my Domino, I would agree with [member=57948]ChuckM[/member].

 

[JimD]

I broke my second 14mm CMT cutter today.  I was cutting a mortise in an old 4x4 post I am using as a desk leg.  It had a small nail that I could not get out.  I hoped it did not go deep enough to get cut but it went less than 1/4 inch into the mortise.  When the bit touched it, it broke.  I consider this my fault but I have also mistakenly hit 2 hardened screws with my Festool 12mm cutter and it is still working fine.  It did not even dull it noticably.  So a relatively soft nail broke my CMT 14mm cutter but hardened screws did not break my Festool 12mm.  Sample of one but seems like a significant difference to me in favor of the Festool.  My first CMT 14mm broke cutting wood, slowly.  It was rapidly replaced under warranty and the second one has cut a few mortises for me without issue.

I did not buy a Festool replacement, however.  I decided to try an Amana.  The Festool was twice as much money.  If I have the same sort of experience with it, I may yet start buying Festool bits. 

 

[Crazyraceguy]

I have never used any but the actual Festool ones. They have always worked well for me. I use mine in a commercial cabinet shop and mostly on sheet goods with the smaller sizes. Sometimes I may use hundreds in just a day or two. As long as you treat the thing well, the bits can last a long time. I just received my 4th case of 6mm Dominos since moving into the new shop. That's 3240 in less than 16 months.
For no more than a genuine bit costs, it's not worth the risk to me. I always have a spare bit, as a back up, because I have hit some random junk inside of ply and particle board once or twice. I even hit a bullet inside a piece of walnut with a router bit one time.
I use it every day, so it sits in the systainer rack at the most easily accessible height.

 

[gunnyr]

I have never used any but the actual Festool ones. They have always worked well for me. ......

For no more than a genuine bit costs, it's not worth the risk to me. I always have a spare bit,.....

I'm with you!  8) 8)  I'm thinking that CMT cutters and making your own Domino's are both false savings.  I have tried (with great success) aftermarket blades on my TS55 and HKC55.  Even so, the Festool blades remain my go to blades for fine work. 

IMHO the blades are part of the system.  Not only that but it is the blade that truly leaves the mark on my finished product.  If I want/need to use a less than premium product I use my DeWalt tools.

 

[JimD]

It's obviously our choice what brand cutters to use.  I think it is also different to be using our tools to make a living versus as a hobby (which is my case).  My track saw is a DeWalt and, after using other blades, I will probably mainly stick with DeWalt blades.  Festool blades may be great but they are a little small for my saw.  But I understand that logic.

Nobody sees the inside of my mortises but me.  But they are as smooth as when I used to make them with a plunge router and much smoother than when I made them with a hollow chisel mortiser.  I've seen one test of gap versus strength and it showed a little more gap actually increased strength.  So I am not sure smoother is necessarily better.  But my non-Festool domino cutters produce mortises just as nice looking as my one Festool bit.

I still haven't purchased tenons yet but I may.  I want a new dining room table and plan to use a bunch of 6mm ones for alignment during the glueup.  I may still make them, it doesn't take much time and mostly uses up scrap I would otherwise discard.  The premade ones worked nice in the 12mm I got with my used domino, however.  If I was making a living with m tools, I would probably buy them.  There are more productive, more money making, things to do than make domino tenons.  But for us hobbists, I think it is a viable option.

I will always make some tenons, however, because I do not like using lots of little ones where I really need one 3 inches wide or more.  Like for a bed frame.  I know that more narrow ones would work but I like using the tenon size I am used to.  I've even used normal integral tenons once with mortises made by my domino.  Worked great.  It's nice to have options.

It doesn't bother me that others want to keep using Festool bits.  I may still decide I want to also.  But as long as CMT or Amana bits work for half or less price, I will use them.  But if I have negative experience with them I will post that.  Not all bargains are really bargains and I do not plan to buy any more 14mm CMT cutters.  The one I paid for gave me some good service but I don't think it should have broken on one small nail.  My 12mm Festool did not on harder material and my saw blades often contact nails without failing catastrophically. 

 

[Wood_Slice]

Amana makes some too
https://www.amazon.com/dp/B086N2W4DG/?coliid=I1ZANRK4KN7Z2Y&colid=3J1AVMZ5RX5RC&psc=0

 

[pdofoto]

I purchased my Domino with Festool 10mm cutter in addition to the standard 5mm. [ unfortunately I couldn't find any emerald editions by the time I decided to buy].
I bought the CMT 4mm cutter and it has been perfect, nice snug fit like my Festool bits. I then went for the CMT 8mm but found it to be a bit loose, the dominoes slide right in without any pressure. It worked fine on the project I bought it for because I was using Polyurethane Construction Adhesive that has great gap filling properties, and it made assembly easy. It was making Fencing for raised planter beds from Siberian Larch. [great for decking, amazing rot resistance, similar to cedar but twice the density.]

I have yet to any projects with the 8's and standard glue, but it feels like the tolerance is close enough to get a strong joint. I think I will take my CMT to my dealer and check both with calipers.

 

[JimD]

I've used all my CMT cutters but never with Festool tenons.  I've used Festool tenons but only with my one Festool bit, a 12mm.  I measured all my CMT bits (and the Festool) and found them to be consistent with the stated size.  I hope you didn't get a "bad one". 

 

[simnick]

My 6mm Festool OEM cutter broke (doing lots of Ipe, can't really blame it), so I bought both the CMT and Amana 6mm bit, and I still have the 2nd OEM 6mm bit as well. Any comparison folks would like me to do?

 

[JimD]

Are all the mortises the same size?  Any difference in fitup with tenons?