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  #1  
Old Tue 17 August 2010, 09:07
Robert M
Just call me: Robert
 
Lac-Brome, Qc
Canada
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Cutting cross grain veneered panels & Baltic ply

Tried a few ways, various type of cutters & speed combo but can’t get a satisfactory cut with as less as possible ( goal is none) wood fiber chip “up” on cross grain cutting veneer panels.

Tried CW, CCW, verrryyyy sssslooooooow cutting, multy depth, cutting 1 past one way to remachining the opposed direction ( CW to remachining CCW).
Tried new cutter ( new upcut carbide).

I think there is no magic solution or approach, but surly a better know way of either I can’t find our getting to old to remember reading about it !

Thanks for your comments & suggestions
(suggestion from ones who has satisfactory cuts, otherwise this thread may degenerate out of the basic of it, HOW TO cutting cross grain veneer panels ! )
Amicalement, Robert
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  #2  
Old Tue 17 August 2010, 09:39
PEU
Just call me: Pablo
 
Buenos Aires
Argentina
Robert, what endmills you used for your tests? flutes?
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  #3  
Old Tue 17 August 2010, 09:51
mikefoged
Just call me: Mike #27
 
Randers
Denmark
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Have you tried up/down cutter, that's what I use, and try with a offset out side toolpath and final cut spot on. I always run with .5mm offset when I cut plywood.

Before final cut
http://www.mechmate.com/forums/attac...1&d=1251470339


after final cut
http://www.mechmate.com/forums/attac...1&d=1251470339

Last edited by mikefoged; Tue 17 August 2010 at 09:54..
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  #4  
Old Tue 17 August 2010, 09:53
smreish
Just call me: Sean - #5, 28, 58 and others
 
Orlando, Florida
United States of America
Robert,
When I have cut veneer in the past, I cut it *sandwiched* between 2 sheets of 5mm luaun or ply or plastic SINTRA (PVC SHEET). This keeps the really thin stuff from pulling into the flutes and burring up. You have a lot of sacrificial boards to use when doing it this way, but sure did work for the last conference table I did.


I also left VERY LARGE tabs on each piece and hand cut it from the sheet with a very sharp xacto knife.


Sean
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  #5  
Old Tue 17 August 2010, 11:07
Robert M
Just call me: Robert
 
Lac-Brome, Qc
Canada
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Obviously not having a vacuum table may not help the bottom portion results of my various tests.
Although Sean approach may seem extreme, I can see a lot of benefit from it. Must admit, did not thought of that basic trick…. The “sandwich” approach !! Thanks Sean.

Mike, do you mean a ‘’Compression’’ type cutter when you say “up/down cutter, that's what I use” ?
Router_bit_types.pdf
Witch feed rate these result been achieved ?
or is this no real consequence ?!? ( say 50 ipm and 250 ipm ?)
I always run with .5mm offset when I cut plywood.
IS the edge cut on cross grains also as nice, hard to tell form the “final cut” photo ?
My test results with this apptoach was not so conclusiv, but was not using a compression cutter either

Robert
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  #6  
Old Tue 17 August 2010, 15:14
mikefoged
Just call me: Mike #27
 
Randers
Denmark
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yes up/down is the same as the compression from your pdf sheet.
my feed rate are 2600mm/min and 18000rpm. to start with, ther will be
some adjustments along the way, until it sound right
The edges are very clean all the way around.
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  #7  
Old Tue 17 August 2010, 18:19
Robert M
Just call me: Robert
 
Lac-Brome, Qc
Canada
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Maybe why I did not get satisfactory results with my compression bit, possibly because it’s another type witch you can see her : Pages from Onsrud_OC-09CatalogR.pdf
Goes to say, little variance can affect a lot !
Thanks Mike,
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  #8  
Old Sat 21 August 2010, 19:43
ger21
Just call me: Ger
 
Detroit, MI
United States of America
You really should be using the shorter bit for more rigidity, but here's what I recommend. Cut CCW around the outside of your part, in a single full depth pass. RPM of around 17000, with a feedrate of 400 to 700 ipm, (10,000-18,000mm/min) depending on the hardness of the material. Slower for baltic birch, faster for softer plywoods or mdf core panels.

Your spindle may not allow these speeds, but that bit is definitely capable of it. I use a n Onsrud 3/8 regular compression at these speeds. The chipbreaker should allow even faster feedrates.

If your cutting in multiple passes, you'll always get chipping due to the upcut portion at the bottom of the bit.

Also, climb cutting (CW) will always give a poorer cut in veneers than conventional cutting (CCW).
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  #9  
Old Sun 22 August 2010, 15:32
Robert M
Just call me: Robert
 
Lac-Brome, Qc
Canada
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Have been doing some testing with various cutter, feed & speed on some Baltic birch panels and some solid wood today, and best I result came up so far ( not conclusive yet, but will not able to dedicate test time for a while) for those BB panels is from a single flute Onsrud compression I have in stock ( see the PDF on thread #7 - #60-152).
At various feed & speed and cutting direction ( CW & CCW ), it gave me overall best results by far…. this far ( downcut cutters included). More to come….

Thought to pass this on at this point.
Amicalement, Robret
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  #10  
Old Mon 13 September 2010, 17:29
ifffff
Just call me: Ivo #38 & #130
 
Parnu
Estonia
I havent cutted plywood much, but best results i had with straight cutter. It gives minimal wood fiber. It depends lot how sharp is cutter, with new one isnt allmost nothing to sand. With spiral cutters is result pretty nasty.

Cutting data:
Two fluted straight cutter 5mm diameter
Spindle speed 18000 rpm
Feed rate 6000 mm/min
Plunge speed 2000 mm/min
Each pass depht 5mm
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  #11  
Old Sat 25 December 2010, 09:08
Robert M
Just call me: Robert
 
Lac-Brome, Qc
Canada
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Copy from anothe post !

My best results cuts with birch Ply are with a compression router bit.
Say your cutting a 6mm multi ply ( birch multi-ply that is), well I use a 6mm compression bit like this one ( see pdf link ) and even with 8mm, 10mm thick birch ply.
If you’re looking for a faster cut in thicker ply mat, say a 10, 12, 15mm or more, then you could consider stepping up to a bigger router bit like a 10 or 12mm bit.
I still prefer most of my cutting w/the 6mm ( Onsrud #60-152) as it allows smaller finish radius.

Any of those bits are design for a single pass cutting. But best finish is obtained with a 1st pass climb cut (CW) as a roughing pass and a finish pass ( remachining) of say +/- 0.5 to 1mm conventional (CCW).
With my set up, best I came up with in this last pass is set up at a slower cutting rate, say feed rate reduced by +/- 50%.

Note : It was explain to me by those bit manufacturer, the difference between a compression “mortise” bit vs a regular compression bit is in the upcut length portion.
( from that same pdf link, look at the 60-100M series )!
A “mortise” bit has longer bottom cut, meaning the position where the up cut meets the downcut is higher in term of cutting depth. A data to take in account when selecting bit vs material thickness vs bit diam !!

Hope this can help clear some of your questions, let me know if I can help you more !
Amicalement, Robert
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  #12  
Old Sat 25 December 2010, 10:17
ger21
Just call me: Ger
 
Detroit, MI
United States of America
Quote:
Originally Posted by Robert M View Post
A “mortise” bit has longer bottom cut, meaning the position where the up cut meets the downcut is higher in term of cutting depth. A data to take in account when selecting bit vs material thickness vs bit diam !!
The bits I buy from www.vortextool.com are the opposite of this. Their mortise compression bits have a shorter upcut section at the bottom, to give clean edges when cutting shallower mortises.
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