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silverdog Tue 09 August 2016 07:27

Z slide cutting errors
3 Attachment(s)
My MechMate #70 have been heavily modified, transforming it from welded frame, to a bolted one.
I am happy with the results but a new problem occurred:
each sequential pass on thick board came "a little bigger" (a slight offset).
I cutted a 19mm MDF board in three 6.5mm pass, each pass is slightly bigger.
All of the sides have the same problem.
I suppose there is a little play on the v-bearings ( a thought I had writing this post :-) ) and the force on the mill push the cut on the outside ...
Any other ideas ?

bradm Tue 09 August 2016 07:47

6mm tool? Have you tried cutting in the opposite direction? Or another finishing pass at full depth?

Tool flex, bearing play, mount flex are the ideas that come to mind.

silverdog Tue 09 August 2016 13:35

Thanks Brad ...
I checked the z axis and there was a little play due to the two upper v-bearing not properly tighted :-)

silverdog Wed 10 August 2016 14:41

.... but it was not the problem ...
My next check is to change the 6mm mill with a 8mm and see, then che software problems .....

silverdog Thu 11 August 2016 12:26

The 8mm mill cut perfectly ! (like never before) you can't see any sign of the multiple pass
So the problem was with the 6mm mill, I think. It wasn't mounted correctly on the chuck.

bradm Thu 11 August 2016 12:35

I've seen lots of flex with deep passes in 6mm and smaller tools. It always surprises me that they don't break.

smreish Fri 12 August 2016 09:12

ditto on what Brad said. I have a good deal of flex on the smaller dia bits when cutting. 5/16 (8mm) or larger seem to always yield better results for me.

silverdog Sat 20 August 2016 09:52

6mm one flute is my most used bit, I have used many times on much harder material than MDF and never had such an evident problems in 6 years.
The problem I had was that the mill was not properly mounted on the ER20 chuck, the same mill gaved no problem once properly mounted. It was my fault :o

IamDave Thu 27 April 2017 23:05

I cut mainly Extira and I use the 2 flute 1/4 and 5/16. The 5/16 really pulls it out and makes a clean cut. Extira I a heavy dust.

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