# How to make better router cuts



## bradleyheathhays (Jun 6, 2021)

I'm in the process of building some molds out of 1/2" acrylic sheet and I'm using pattern pieces and a straight cut bit on my router to cut the acrylic to size (first time I've done this btw). Although I know my pattern pieces are good and straight (come from a pro cabinet maker) the acrylic ends up having little ripples on the cut face no matter how little I try to take off at a time. Since the patterns are good I guess the problems got to be with my setup.

I'm running a Dewalt DW616 1.75? HP router on a flimsy Skill RAS900 router table that weights maybe 15 lbs. and not held down. The bit set was cheap off amazon and unfortunately has a 1/4" shank.

I'm guessing I need to at least screw the router table down and use a 1/2" shank bit. Any other suggestions?


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## trc65 (Jun 6, 2021)

I think a spiral cut bit would give you a better cut. Lots of companies advertise bits specifically for plastics.

Reactions: Agree 2 | Useful 1


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## 2feathers Creative Making (Jun 6, 2021)

Also direction of travel will affect cut immensely, but you probably already know that. The type bit and speed of travel will do more than amount.of material being removed.


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## Mike1950 (Jun 6, 2021)

cheap bits produce crappy cuts and sometimes become shrapnel.

Reactions: Agree 3


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## DLJeffs (Jun 6, 2021)

I've not cut any acrylic with a router but another problem might be heat. Acrylic melts easily. I suggest cleaning out the chips constantly to reduce the heat buildup. An upcut spiral bit as Tim suggests would also help remove chips from the cutting area.


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## gman2431 (Jun 8, 2021)

You need an O flute cutter.


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## barry richardson (Jun 8, 2021)

You might have an out of wack bit from poor machining or a hard catch. Also your "flimsy" router table might be causing chatter....


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## bradleyheathhays (Jun 14, 2021)

Thanks for all the good advice.

I guess the good news is there's lots of room for improvement.

I've had a lot of suggestions for a O flute upcut bit but despite all my searches I don't believe there's one of these made that's designed to be a trim bit, with a guide bearing. All of them I found were meant for CNC. The closest kind of bit I can find to what's been suggested is something like the Whiteside RS5200 1/2" shank 1/2" bearing 2" cutting surface length. If a O flute upcut can't be found would this do?...


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## gman2431 (Jun 15, 2021)

You could use a guide bushing, but then you would have to account for the offest. It might be easier to adjust your templates than to chase bits... The 2 flute you pictured will still show tool marks.


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## frankp (Sep 16, 2021)

I always cut acrylic with a bandsaw and a high TPI blade. With a router I'd definitely go with a flute bit and maybe play around with the speed to see how much of an affect that has. I suspect DLJeffs is onto something with the heat.

EDIT: Good grief, I didn't realize the OP was from June. Did you ever figure out a good solution?


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## gman2431 (Sep 16, 2021)

frankp said:


> I always cut acrylic with a bandsaw and a high TPI blade. With a router I'd definitely go with a flute bit and maybe play around with the speed to see how much of an affect that has. I suspect DLJeffs is onto something with the heat.
> 
> EDIT: Good grief, I didn't realize the OP was from June. Did you ever figure out a good solution?


O flute cutter. Lol

Reactions: Like 1


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## bradleyheathhays (Sep 19, 2021)

Hey frankp, yes gman is right with the 0 flute bit. That's the best solution I've been recommended. For my situation I ended up steadying my router table more and ended up with better results. Surprisingly, although heat buildup was something I got lots of warnings about I saw none cutting my patterns.

Reactions: Like 1


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## Nature Man (Sep 19, 2021)

bradleyheathhays said:


> Hey frankp, yes gman is right with the 0 flute bit. That's the best solution I've been recommended. For my situation I ended up steadying my router table more and ended up with better results. Surprisingly, although heat buildup was something I got lots of warnings about I saw none cutting my patterns.


Can you share pics of your project? Would really help to visualize what you are talking about. Chuck


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