Cutting polycarb need new idea's.

[knight_toolworks]

I have cut a fair amount of it and it is never a great thing. it tends to be grabby and usually does not cut smooth and it tends to come loose.
I usually do double sided tape or spray adhesive. But this job I am bidding on I know will not allow the cost of that and it is about 6 sheets to cut so not super practical.
I got a deal on onsrud 0-flute downcut bits .15 so that should help a fair amount. but not sure if even then a vacuum will keep them from vibrating.

[gundog]

I have cut a fair amount of it and it is never a great thing. it tends to be grabby and usually does not cut smooth and it tends to come loose.
I usually do double sided tape or spray adhesive. But this job I am bidding on I know will not allow the cost of that and it is about 6 sheets to cut so not super practical.
I got a deal on onsrud 0-flute downcut bits .15 so that should help a fair amount. but not sure if even then a vacuum will keep them from vibrating.

Hi Steve,
I think I would use an up cut bit you may have issues with re-welding with the downcut. Onsrud makes special bits for cutting plastic and they have worked well for me. They have charts on their site for choosing the right bits for the type plastic you are cutting. I cut soft plastic but they list bits for polycarbonate.

Here is a link to their page http://www.onsrud.com/plusdocs/Doc/index.html?model.code=plastics they list downcut bits but my experience has not been good with the downcut bits using vacuum because it does not get the chip out of the cut and it re-welds.

Mike

[Brady Watson]

I usually do double sided tape or spray adhesive. But this job I am bidding on I know will not allow the cost of that and it is about 6 sheets to cut so not super practical.

I got a deal on onsrud 0-flute downcut bits .15 so that should help a fair amount. but not sure if even then a vacuum will keep them from vibrating.

If this job won't cover hold down costs, then...don't take the job. Honestly, why do that to yourself? Depending on the part, it may require both DS tape, some sacrificial material AND vacuum to hold it down properly to get a quality edge.

You certainly do not want to use a down cut for this job, unless the material is very thin and the bit is a little larger than you need to get proper chip clearance. If it is over 3/16" thick, forget the down cut. The cost of proper tooling should be built into the cost of the job. What good is bargain tooling on jobs where you make no profit? Profit is not labor exchange.

I've given enough parts away over the years to know this job sounds like an albatross right out of the gate. It's never a good thing when customers are shopping on price alone, especially on a 6 sheet job. If it was a 600 sheet job, that would be different. You are doing this work to make a living, aren't you? Sorry if I sound practical...

-B

[MogulTx]

I did a whole bunch of cutting the other day on 1/4" acrylic and got good results from an onsrud 1/8" upcut, designed for plastics.

And it seems like piling on, but Brady is right. If they are beating you up using price and all that- then are you giving your work away? Are you going to have to buy a sheet of material out of the deal? Will that put you into negative numbers? Be aggressive, but be smart, too.

I have done jobs literally for nothing- and on most of them it was intentional. I am my own biggest customer (real customer). And I charge myself a real rate. It doesn't make sense to do otherwise...

[knight_toolworks]

I had tuned down this job several years ago because I could not keep the parts in place. but I have learned a lot since then. the thickness is only .09 so downcut may work well and it is a onsrud downcut o-flute for soft plastic and the bits only cost me 11.00 for 5 of them. The customer will supply the material and he is going to bring the vacuum jigs the last guy used over.
if I can make the vacuum work it may not be too bad. but I plan on testing it with some scrap before I commit.

[genek]

Here is some labor rates for different professionals look at the rates got to the other link it suggests.

http://viewer.zmags.com/publication/a878b7af#/a878b7af/12

[genek]

By the way that is what a Company is supposed to pay a employee.... not what you charge the customer.
set rates according to standards not what the customer wants. you need to make money and your employee's need to make good money... if you do not have employee's you had better charge as if you do. at some point you will need to have employee's and if you have not established that type of pricing you will go broke real fast.. customers accept small increases but if all of a sudden you are charging 4 times the rate they are used to you will lose them.

[knight_toolworks]

I charge 60 to 120 or more a hour depending on the job. Plus all expenses if there are any. But last time I found I could not get 60 a hour doing this but I don't remember much of what I had tried to do with this job.

[gundog]

Steve you can bring a sample over to my shop I have a small assortment of plastic cutting router bits and a vacuum hold down table we could run some test cuts if you like.

Mike

[knight_toolworks]

Thanks for the offer but you are a bit far to travel. I don't have problem cutting it but more holding it in place with just using a normal vacuum table or simple vac jig.
if I can't do it without the usual methods then it would be cost effective.
just got this in. I think it is about .15 I would like smaller but these were so cheap it is worth it to try. I mean how can you beat 5 of these for 11.00?
just waiting on the metric collet.
http://i154.photobucket.com/albums/s266/knighttoolworks/posting/null_zps1a60b4d6.jpg (http://s154.photobucket.com/user/knighttoolworks/media/posting/null_zps1a60b4d6.jpg.html)

[jerry_stanek]

Have you thought about using a pressure foot

[knight_toolworks]

I have used the foot but if the material is lifting up like the polycarb does it will not keep the vacuum going. once the sheet starts vibrating shavings get under it the game is over.
I have got a lot of stencils out of .03 polycarb with the pressure foot. with a small amount of text it works fine but when you have a ton of text then it fails and it is time to stick the sheet down.
Well I got the downcut 0-flute from onsrud only to find they had them mislabeled and they are upcut. still a great deal even with the metric collet I needed.
So I contacted them through ebay and the rep was really nice and is sending me 5 1/8" downcut 0-flutes for free.
I cut it with a 1/16" downcut standard bit and it stays in place but leaves a burr. these can't have a burr on them.

[knight_toolworks]

finally got the downcut o-flute and the right collet and the stuff cuts well and stays in place.
http://i154.photobucket.com/albums/s266/knighttoolworks/posting/null_zpse7849477.jpg (http://s154.photobucket.com/user/knighttoolworks/media/posting/null_zpse7849477.jpg.html)