Countersinking Confirmats in Melamine

Troubleshooting a problem with getting cabinet assembly screws driven flush. September 28, 2009

Who is using confirmats in melamine? The screws we are using seem to require countersinking by hand at the assembly bench to get them really flush. We get confirmats with nibs and a sharp point. Could this be an issue with the screws themselves? We are drilling a 7mm hole in the side of each cabinet and end boring on a Gannomatt. What is going on here?

Forum Responses
(CNC Forum)
From contributor J:
How is this relevant to CNC? Obviously, the screws aren't (completely) self-countersinking as advertised. Also, melamine is a finish.

From contributor U:
There are some confirmat drill bits for boring machines available from Amana, but when I used them they did more harm than good since the bits were not a V-bit. I would imagine there must be other sources for these bits that have the 10 / 7 / 5 mm steps for this process. Even just the 10 / 7 mm would do it with a V-bit. I am a small shop so I just do the 10mm countersink by hand.

From the original questioner:
Sorry I wasn't clear enough. The 7mm holes are being bored on a CNC in a nest, the horizontal holes are done on the Gannomatt. In any case, the 7mm thru hole is done from the "inside" of the cabinet in the nest so hardware can be drilled too. Since I am on a spoilboard, I use brad points in my drill bank with no chipping on the back of the part. It would be more trouble than it is worth to flip the parts for countersinking on the machine.

Sounds like you are doing the same as we are, and countersinking after by hand. This is just what I am looking for, the experience of people who use confirmats. The nibs on the confirmat screws for countersinking have worked very well for me in the past, but do not seem to be working now. I am wondering if it is the brand of screw, the brand of melamine, (the brand of melamine coated flake board and melamine coated MDF) or something else. Is anyone having success with this or does everyone sink the heads flush with a countersink by hand?

From contributor U:
Since you are using the CNC to drill the 7mm holes I guess you could just do a flip and put the countersink on the other side, but that sounds like a pain. Yeah, maybe it is your screws. You might try a different brand.

From contributor S:
We drill through with 7mm bits on our CNC. Our build-up guy uses the small, Makita battery impact driver and they sink fine. In fact, if you don't have the clutch set right, you can run it all the way through the panel.

From contributor L:
What is the substrate of your melamine board? Fir or pine?

From contributor M:
We thru-bore on 2 PTP machines using 8mm v-point bits; no problem with flushing the screw during assembly, and a little bit more adjustment for uneven material. We’ve never had any strength issues over 20 years. Also, the above thread suggesting an impact driver for assembly helps a lot.

From Brian Personett, forum technical advisor:
I've used both sizes of Confirmats over the years and never had an issue with either one. We also use an impact driver. The clutch has to be set. It's very easy to run a Confirmat right through the board.

From the original questioner:
I will try a new brand of screw to start with, it is really puzzling me to have this issue. Contributor L - I am using Tafisa melamine I don't know what the core is made of offhand. It machines very nicely and I have used it very successfully with confirmats in the past. I doubt that has anything to do with it, but I am willing to consider all possibilities.

Contributor M, S, and Brian - I do prefer the impact driver too. Most of the bench guys here are using regular drivers. I think the screws should work fine with a standard driver, but yes the impact drivers are nice. Do you find that it is a problem in your assembly if you drive the screws with a regular driver? Contributor M - I know another guy that uses 8mm for the thru hole too. He likes the ability to fine tune the lineup and deal with small machining variations. I try to work a bit more precisely but I bet the little extra room allows for better sink too. It's something to reconsider perhaps on my part.

From the original questioner:
Contributor L - it seems Tafisa is Yellow pine. What are your thoughts?

From contributor S:
The only thing I find with a regular driver is when the battery starts getting low, you lose the torque and if the guys aren't on top of it, it won't set the screw head flush.

From contributor L:
We used confirmat construction exclusively because of our machinery setup. We now use dowel construction. If you have any scrap board in your shop that has a fir core you might run a test cabinet and see if that solves your problem. While we used confirmat construction we could only use Fir core board due to the tensile strength of fir vs. pine. Every time we tried pine the confirmat would strip out and would not countersink itself. Give it a try and let me know.

From Brian Personett, forum technical advisor:
I've been using Tafisa for a couple of months, I saw no difference when I switched. I've used Panlolam, Panval, Roseburge, and Duramine with not much difference in screw performance.

We dabbled with standard battery drivers when we first switched to Confirmats. I have a couple of real beefs with the battery drivers. First as has been stated as the batteries start to lose their charge, you're constantly monkeying around with the clutch, if you can get them to sink at all. Secondly is the weight. After you wrestle the components, cabinets, and a heavy battery operated driver around all day, it wears you out. We bought a couple of small, lightweight, pneumatic impact drivers, all problems solved. I found another driver that I fell in love with, but couldn't get past the 1300 dollar price tag.

As far as larger holes for fudge factor, I've never done it, I just bore whatever size it says to bore. We only use the smaller confirmats now. Sides get a 5mm hole, horizontal parts get a 4mm hole. I prefer to have everything dialed in, I don't like trying to make non-aligned parts line up. We just set the parts up and start screwing.

From the original questioner:
Great responses, thank you all! Here are the results of some informal experiments with 7 mm thru holes and 5 mm horizontal bore:

1) Tafisa (pine core) Melamine side Tafisa Rail, standard screw gun: Makes a mess and pulls threads right out of the horizontal member nearly every time.

2) Tafisa Melamine side Tafisa Rail Pneumatic drill: Perfect results, can set the screw in the side even with a Horizontal grade Plam face.

3) MDF side with veneer face and MDF rail Standard screw gun: Works fine as long as the screw is set gently, otherwise the screw threads break the MDF rail. No problem with the Pneumatic drill.

4) Tafisa side MDF rail standard screw gun: Makes a mess, the MDF has not the guts to pull the screw through the melamine face and the rail splits every time.

5) Tafisa side MDF rail and Pneumatic impact driver: No problems can set screw without breaking rail.

6) Generic unknown random raw flakeboard (presumably not pine core) rail and Tafisa side: standard driver sets screw.

7) Melamine face and VC plywood rail. Screw sets well with standard screw gun.

Informal Conclusions:

Pneumatic driver will work in every situation I tried. Standard screw gun works less well the softer the core and the harder the face the screw has to cut through. It doesn’t seem to be the screws since they work well in some materials and not others. It does seem to be the core of the rail, since in a different type of flake board the screws grab better and will set the screw. I think it is the pine core as contributor L suggested that is at issue. I think all of the other guys are using impact guns and have no issues no matter what core, even MDF. I should be using impact too. I do not think I want to expand the holes to 8mm, I like the lineup as it is. I like all of the other properties of the Tafisa, it is consistent in thickness, machines well and the faces are well bonded, so I do not think I will be advocating a supplier change. I still plan to try another screw, and do some more experiments with other brands of melamine.