Blind Dado question????

[Damon Nabors]

I had everything dialed in perfect and then I switched materials on a project and everything goes to S@#t! I don't know if my tennons are too long or the dado's are too shallow, either way the parts do not fit. The tennon thickness and the dado width are perfect, but the tennon bottoms out in the dado. When I wrote the CNC file, it asks to change material thickness and I always mic the material and input the correct thickness. How do I double check the number I entered?

Any Ideas on what could have happened?

At this point I am left edge sanding all the tennons so they do not bottom out.

[Mark Taylor]

Damon

There is a known problem with the dado and tenons when changing material thickness headed into the twd file.
The best work around to this is to find an avg. thickness for all your materials and build your cabinets accounting for the actual material thickness.
Sorry you found out about it the hard way...it's been an issue for some time now.

Mark

[Damon Nabors]

Yea, that really sucks (sorry) considering I now have 20 sheets of parts that do not fit. At least I can salvage them by trimming the tennons. I am glad to know that there is a problem. I am going to go have another beer now and settle my nerves.

[Jason Susnjara]

Hi Damon,

Sorry to hear about the problems that are having. There could be numerous items that can cause this to happen. Spoilboard thickness, daylight value for the tool, material thickness, etc... What Mark says is correct. You should take an average of the 20 sheets and use that number but I don't think that is the problem here. I will have someone give you a call about this and we will try to figure this problem out. The tech will probably want your eCabinet files as well as your cnc files and twd files for this job. If it is a bug, we will try our best ot fix the problem.

thanks,

[Damon Nabors]

Hey Jason, thanks for the reply. I sent the files over to Todd. I double checked the daylight values and they are good. I touched off on the spoilboard to see if the Z axis was the same as the daylight on the tooling and they are within .003.

The problem seems to be in the dado depth. I set a dado depth of .3125 w/.015 clearance and the dado's mic at .29 depth, too shallow.

Thanks for your help.
Damon Nabors

[DanEpps]

Hmmm...

.3125 - .015 = .2975

[Jason Susnjara]

Hi Damon,

I'm sure that Todd will be able to help you out on this problem. Just keep us posted.

thanks,

[Michael S Murray]

Damon,do not use the material thickness change at the twd stage, I have not used it for a year and then the other day a cutting customer through me a curve, I used it and ended up with Dados the same width as tenons. This was supposed to be fixed a while back but must still have problems. Just average your sheet goods and go with that, have not had any problems doing it this way in a long time.

[Damon Nabors]

Dan, If I understand it correct and maybe I don't, but

.3125 + .015 = .3140 Hmmmmmm.

Is the fit clearance adding to the dado depth or subtracting from the tennon length?? I don't know the answer here.

Thanks,

Damon

[DanEpps]

I think it is added but I just thought it strange that it was so close if you subtracted...

[Damon Nabors]

I thought the same thing Dan, but I have found in the past if I think too much, the problems get worse. I truely don't know what direction the clearance is suppost to go. I guess it could reduce the tennon to prevent blowing through the material with too much clearance and too deep of a dado.

[Rob Frenette]

Damon

I agree sometimes if you think to much things get worse I belive the depth clearance is added to the depth of the dado. we add .030 to the depth to compensate for tool daylight, spoilboard, and variances in material thickness, although the last item has more effect on fit clearances. Have not used the change material before twd output for awhile but i think one of my customers used it one time and got the same result, tenon bottoming out. Hope this gets fixed on the next update.

[Mark Taylor]

As Mike said, this problem has been on going for some time (well over a year now)...Forest was the one to warn me about it and suggested I determine an avg "mic" for the materials I use and then construct my libraries with those materials and thicknesses...we use 0.02 on our fit clearances and haven't had a single problem since starting to work this way.

I do use the change material thickness sometimes - but never when it effects joints. IE. when I send something to the machine I know is going to the profile modeler - I'll add the thickness of the waste board when writing the .twd - because the profile modeler doesn't account for the waste board. I've never had a problem using it in manner like that.

Mark

[Todd Miller]

Hey Jason, thanks for the reply. I sent the files over to Todd. I double checked the daylight values and they are good. I touched off on the spoilboard to see if the Z axis was the same as the daylight on the tooling and they are within .003.

The problem seems to be in the dado depth. I set a dado depth of .3125 w/.015 clearance and the dado's mic at .29 depth, too shallow.

Thanks for your help.
Damon Nabors

Damon,
What was the thickness of the material that had the .29" depth? What that material less than .56 thick"?

[Damon Nabors]

Todd the material measured .56 . After doing some test cuts today, Dan and I are both correct. When I originally designed the job, it was built with 3/4 material and 1/2" backs. I later changed the material in the "Detail Room Editor">"Change Material">"sheet stock", I changed the 3/4 and the 1/2 to 5/8" material, wrote the CNC FIle and changed thickness to .56" when prompted to change material thickness. The dado depth was set at .3125 w/.015 clearance. The dado ended up .2975 when it should have been .3140.

Today I cut some test boxes with 3/4 and 1/2" material like I normally do and changed the material thickness when writing the CNC Code. The boxes turned out perfect. I had a .375 dado set up with a .030 clearance and it measured .3999 after it was cut. What I found out was, if you add the clearance, it adds to the depth of the dado.

Now it get Harry, If you change the sheet stock to something totally different, it will subtract the clearance from the dado instead of adding to it. Causing the dado to be too shallow.

I even took the 3/4 material that I had the cabinet designed with and updated the material thickness to .56 when writing the CNC Code DID NOT CHANGE SHEET STOCK, ONLY UPDATED THE MATERIAL THICKNESS And it worked ok, so that tells me the material thickness update function works good, but the sheet stock change does not.