Fit Clearance and small shoulder

[frank134]

Ok so I am up and running with e cab. Cut out a few boxes from some oak and they turn out ok. So then I switch to some cherry and it was off from the oak by .002. The Dado and Tenon are really tight. Is there a formula at what to set the fit clearance or do I have to just keep track of the difference thicknesses of the plywood? Also there a small shoulder at the end of each Tenon how do I get rid of it.
Thank for any help.

[Gary Campbell]

Frank...
Looking for a little more info here....

You say off from Oak by .002. Can you explain further?

Were the 2 files cut with the same dado %, depth & fit clearance?
Was the bit changed or the tacle surfaced btween the 2 files?
Do you zero to the top of the material or the spoilboard?

The plywood thickness has no effect on the dado/tenon fit. The settings, the accuracy of your Z zero have much more effect on the dado accuracy.
You may want to re-mic the parts to see if they are the same thickness as the design value.

What is material thickness?
What is tenon %
What is actual thickness of tenon as measured with a digital mic?
(the tenon thickness should be the mtl thickness * dado%. My guess your actual is thicker.)

When the outline cut and tenon dado do not line up at the tenon shoulder it is almost always a mechanical issue. Usually the X. Double check pinion to rack clearance and your pinion grub screws.

[frank134]

ok. First I sorry I am running blind dado.
the .002 is the difference in thicknesses between the too plywoods.
yes the two file were cut with the same dado% and fit clearance
the bit was not change and I rezero to the top of the material

I have to take a pic of the last thing as I don't know how to say it.

[Gary Campbell]

Frank...
I am pretty sure that I know, and have seen your problem. Check the pinions and grub screws. If the X are loose, check the Y also. I will be at the shop in the morning. Call if I can help

[frank134]

Picture 12.jpg

I hope this work. gary this is the problem I have been having. How do I get rid of this?

thank
frank

[Gary Campbell]

Frank...
Only 2 causes for this, as far as I know.
1) Mechanical (most likely) check pinions and grubs as above. Make sure parts didnt move. (is tenon similar on other end of part?)

Mic the tenon and see how it compares with your design value
Did you mic the tenon thickness?

2) when using different bits for outline & dado, 1 has size listed improperly

I am sure that 1) wins in your case

[frank134]

the part did not move and all the tenon are the exact same. Everthing on the machine is as tight as I cam get it. there no movement of any kind. and all the cut are very precise. all tenon are the exact same all seven. so when I but them together i have a little should at each end. Rasing the center. I am using the same bit for both job. there has to be a setting some where to set the tenon depth into the material.

[Gary Campbell]

Frank...
Have you mic'd the parts that I requested?
I need the material thickness (design)
Tenon % (design)
Measured tenon thickness
Measured tenon length

[frank134]

as soon as I can get back in the shop tommrow I will get what you ask for.
thank

[frank134]

Ok Gary I think I got what you want to help me.
e-cab setting
Dado depth .375
Depth clearance .025
Fit clearance .03
Thickness % 53
Link setting
.05 dovetail radius crunch
100 male dove feed rate
.05 materialdraw picture of dado.pdfPicture 16.jpg
Picture 14.jpg

Picture 15.jpg

Picture 16.jpg