Domino technique - is there a wrong way?

[Phil Harding]

I apologize to all who are sick of the Domino threads, but I need a little help sorting this out. I received my Domino in early April like many of you, but I really haven't had a chance to use it (other than the obligatory trial mortises I cut when I first received it). I started a project to build a stereo cabinet this weekend and I was looking forward to using the Domino for most of the joinery. However, I can't seem to cut a clean mortise. I tried cutting 5 mm thick mortises at the standard width - no problem. I then tried cutting at the +6 mm width setting. The Domino chattered quite a bit and the mortises were not as clean. At the +10 mm width setting the tool chattered so much that I ended up with "S" shaped mortises or mortises that were of uneven depth. In fact the chatter was so violent that it broke the tip of the cutter.

I tried the 6 mm cutter and the got similar results. I call Festool and talked to a tech who suggested that the problem is most likely technique and less likely a malfunction of the tool. I can accept that for now because I was able to get clean mortises when I played with the 8 mm bit and a very slow plunge rate (much slower than I would normally use for my PC biscuit joiner). So here's my question - what's the best techniques for getting a clean mortise regardless of depth and width?

Thanks in advance for your suggestions.

[Glen Blanchard]

I will let the more experienced folks chime in here, but if you get clean cuts when mortising with the narrower setting, but are encountering problems with the wider settings, that does not sound like technique to me. Sounds like a problem with the machine.

[Bob Childress]

It IS important to use a slow plunge rate, but that being said . . . I have had no problems and no chattering. Sounds to me like a malfunction may be occurring. However, let's check one thing more:

You ARE changing the mortise width setting WITH THE MOTOR RUNNING are you not?

If you don't, damage to the machine may occur.

[Ted Miller]

Phil, Yes I do plunge slowly, depending on the stock species you are using. Of course the harder the stock the slower I go. Plywood has some voids and will cause some cutters to go in quicker in some areas of the plunge.

If you try to go to deep with a smaller bit then the tenon can get oval in shape.

When setting the cutter width make sure that you are making that adjustment while machine is running.

Whether I am making 6 tenons or 100 I start the machine, let it get to speed then I start to plunge slowly and I back out slowly. I use two hands one to push down the fence and of course the other near the power cord. My hand is rather large so I have to hold my hand back a bit farther then most to be able to finish the tenon.

These cutters should last you 1000s of cuts, I have cut hard and soft woods as well as tons of plywood without a problem except with through tenons. Then I move up to a larger bit...

[Gary Keedwell]

Phil, Yes I do plunge slowly, depending on the stock species you are using. Of course the harder the stock the slower I go. Plywood has some voids and will cause some cutters to go in quicker in some areas of the plunge.

If you try to go to deep with a smaller bit then the tenon can get oval in shape.

When setting the cutter width make sure that you are making that adjustment while machine is running.

Whether I am making 6 tenons or 100 I start the machine, let it get to speed then I start to plunge slowly and I back out slowly. I use two hands one to push down the fence and of course the other near the power cord. My hand is rather large so I have to hold my hand back a bit farther then most to be able to finish the tenon.

These cutters should last you 1000s of cuts, I have cut hard and soft woods as well as tons of plywood without a problem except with through tenons. Then I move up to a larger bit...
Apology accepted. You might get a better response if you go to Festool Owners Group web site.
Gary K.;)

[Rick Christopherson]

Phil, I believe that your problem is that you are plunging too fast. As you said, you were comparing your plunge speed with what you could do with a biscuit joiner. This is too fast for this type of cutter.

The larger the bit, the more noticeable an over-speed plunge will be, especially in non-homogenous materials such as plywoods. The edge of the cutting tip catches on end-grain fibers and deflects the bit. The reason why this is more noticeable on the larger bits is because the tip has a more aggressive cutting surface.

Getting some chatter, within reason isn't going to have an adverse effect on the mortise, but excessive chatter will enlarge the mortise.

P.S. Turning the mortise width dial with the machine not running does not automatically damage the tool. However, forcing the dial to turn will damage the tool. Depending on the alignement of the eccentric yoke, the dial can be turned when not running---just don't ever force it to turn!!!

[jason lambert]

Yes plunging fast will do that. I was able to really quickly cut in biscuts with my dewalt biscut joiner. The fest I have to go alot slower and really control the speed of the cut. It requires a little more attention. I would say this is the only downside to this tool but is well worth the better joint. Also what wood are you cutting into? If you are cutting slow I would bring it back to the dealer and have him look at it.

[Dennis Peacock]

This is an interesting "downside" to the Domino. I haven't ordered one, but kinda waiting to see how it goes 'after the dust settles'. :D

[Phil Harding]

Thanks to all who offered suggestions. I'm traveling on business for the next few days but will get a chance to play around with technique when I get back on Wednesday.

-- Phil