# Plastic Routing - Avoding Catching / Accidental Climb Cut



## router_newb (Nov 18, 2014)

Hello,

I just bought a table router (Taskforce) for cutting some plastic material (Kydex). I don't have 'woodworking' experience and had never used a table router before. 

The issue I have with the material is that as long as I am using a conventional cut and taking reasonably deep passes it cuts smoothly. However, if the work part gets out of flat with the table, I take too deep a cut, or I accidentally climb cut (say during a corner operation) it quickly grabs the work piece and becomes nearly unmanageable. Recently, this lead to chipping part of my work piece, not to mention timidness of working with this material.

Currently, I am using a 1/2 Straight Flush trimming bit with top bearing. I am doing all my cutting using a MDF template. I try to get the material close using a jigsaw, but I still have about 1 OD of material left over. Have tired cutting speeds between (11k-18k RPM). Material thickness is .186".

Doing some research it looks like a spiral bit can help cut down on catching/kickback. Since I don't have any previous routing experience can anyone provide insight as to using a spiral bit for solving this problem? In addition, for my usage would a down vs up spiral make a difference, I am assuming I would want the one that pulls the part into the table?

Thanks in advance.


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## Semipro (Mar 22, 2013)

Hello Brandon, welcome to the forum.
You say no experience?
Well are you feeding your piece left to right?


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## Stick486 (Jan 4, 2013)

Semipro said:


> Hello Brandon, welcome to the forum.
> You say no experience?
> Well are you feeding your piece left to right?


wonder if he is using a starter pin???

Using a Router Plate Starting Pin - NewWoodworker.com LLC

Safer Routing with a Router Table Start Pin - YouTube


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## Cherryville Chuck (Sep 28, 2010)

If the amount you are routing is more than 1/2 the diameter of the bit it could be causing you problems. For example, if you are using a 1/2" bit I would only want to rout off a 1/4" overhang or less.

Onsrud makes bits with special geometry for cutting plastics. Their customer service people are some of the most knowledgeable and helpful you can find. If you google Onsrudcutter2010 you should be able to find them.


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## router_newb (Nov 18, 2014)

Semipro said:


> Hello Brandon, welcome to the forum.
> You say no experience?
> Well are you feeding your piece left to right?


My work part is a ‘frame’, so on the inside I move the part ‘clockwise’ around the bit, and the outside cuts I move the part ‘counter-clockwise’.


Stick486 said:


> wonder if he is using a starter pin???


I am not using a starter pin, and had never heard of one before. Looks like it something I could benefit from, but the only holes I have near the router are one of the three that mount the router to the table. Not sure how that would work on my setup.



Cherryville Chuck said:


> If the amount you are routing is more than 1/2 the diameter of the bit it could be causing you problems. For example, if you are using a 1/2" bit I would only want to rout off a 1/4" overhang or less.
> 
> Onsrud makes bits with special geometry for cutting plastics. Their customer service people are some of the most knowledgeable and helpful you can find. If you google Onsrudcutter2010 you should be able to find them.


I try to cut a half diameter per pass, and take multiple passes, but doing by hand it is hard to control the depth every time. 

Good call, looking back at the Kydex recommendations and I just realized they direct back to an Onsrud website. 

Found a list of recommended bits on Plasticrouting.com, unfortunately none of those have bearings, but that gets me down the right path of what kind of bits are recommended.

Can't link the search results because of post count, but maybe the text will format OK:

Part # Material Color Thickness CED S \ F Ranking Helix RPM Feed D / P Direction Price
61-041 Kydex V #52065 Black 0.125 0.125 22 1st Straight None 18000 100 0.125 Conventional $23.10 
63-710 Kydex V #52065 Black 0.125 0.125 21 1st Spiral Up 18000 100 0.125 Conventional $23.35 
63-710 Kydex V #52065 Black 0.125 0.125 24 2nd Spiral Up 18000 100 0.125 Climb $23.35 
63-760 Kydex V #52065 Black 0.125 0.125 24 2nd Spiral Up 18000 100 0.125 Conventional $23.35 
56-081 Kydex V #52065 Black 0.125 0.25 17 2nd Straight None 18000 100 0.25 Conventional $22.20 
61-081 Kydex V #52065 Black 0.125 0.25 16 1st Straight None 18000 100 0.25 Conventional $24.75 
63-724 Kydex V #52065 Black 0.125 0.25 18 2nd Spiral Up 18000 100 0.25 Conventional $22.25 
63-774 Kydex V #52065 Black 0.125 0.25 14 1st Spiral Up 18000 100 0.25 Conventional $22.25 
52-638 Kydex V #52065 Black 0.125 0.375 19 1st Spiral Up 18000 150 0.125 Conventional $41.35 
56-121 Kydex V #52065 Black 0.125 0.375 14 1st Straight None 18000 150 0.125 Conventional $42.35 
52-650 Kydex V #52065 Black 0.125 0.5 20 1st Spiral Up 18000 200 0.125 Conventional $71.80 
56-162 Kydex V #52065 Black 0.125 0.5 17 1st Straight None 18000 200 0.125 Conventional $68.95


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## Quillman (Aug 16, 2010)

Your stock is so skinny I'm surprised you're have so much trouble. Too many surprises for the novice with spirals on plastic; avoid them. Dead bits and deep cuts are especially likely. Start over with new cutters and take no more than 3/16 x 3/16, until comfortable. 
I cut plastic for a living, speaking here from experience. 
Lighten up, slow down, run at max RPM and study the total pathway of the cut before starting out. Can you manage the down and against the cutter forces for the whole trip? If not, ace this control until you have it.

Would advise pin-routing if you have the patience to set up for it (and the equipment). A bearing on a 20,000 RPM spinning arbor is nuthin' but chatter.


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## router_newb (Nov 18, 2014)

Quillman said:


> Can you manage the down and against the cutter forces for the whole trip? If not, ace this control until you have it.
> 
> Would advise pin-routing if you have the patience to set up for it (and the equipment). A bearing on a 20,000 RPM spinning arbor is nuthin' but chatter.


For the most part I don't have any issues cutting against the bit, although I will admit my technique needs development. It has gotten better but I don't doubt that it might be much of my problems. 

However, with my setup I have to rotate the piece around the bit and sometimes I have to push the part at 45 degrees and it is hard to maintain strict control over the cutting depth while still feeding the right direction.

Also, sometimes the part becomes uneven with the table and that leads to catching. Some of that is my technique but partly that my table top is small and the part has to over hang the edge. 


Will consider pin-routing, never heard of it before, as I do end up with chatter on my finished edge. It looks like it would make some things easier if I can adapt it to my setup.



Quillman said:


> Too many surprises for the novice with spirals on plastic; avoid them. Dead bits and deep cuts are especially likely.


What are dead bits / deep cuts ? With more experience would a spiral be safer?


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## Quillman (Aug 16, 2010)

My haste made waste. Dead bits and deep cuts are causes for bad plastic cuts.
Spirals buy you next to nothing, even with experience. Don't count on a spiral for a better cut. If your work is hanging off the table and is a balancing problem: STOP.
Get control of the entire cut before you start the motor again.


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## router_newb (Nov 18, 2014)

Thanks for all the feedback. I am going to start by adjusting my setup to ensure I keep the part flat and try to reduce the amount of routing I need to do. As well, for the routing cuts I will try to slow my cuts down and take more time. 

Found some new cutters, will stick with the straight flush trim cutter. Out of curiosity what are some of the signs of when a cutter is bad/dull?


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