Bobbin Support

[Possum]

>>>>>>>

its pretty hard to cut a perfectly straight piece on a band saw. the parts we're talking about here are .25" thick by usually .25" tall x about 2.5" long. Tap does cut the stuff on a table saw but they use a special blade. I'm not sure a high speed anything would work on polycarbonate it doesnt like heat either. I quit making most of those pickups due to the problems with tapping it.....

[madialex]

its pretty hard to cut a perfectly straight piece on a band saw. the parts we're talking about here are .25" thick by usually .25" tall x about 2.5" long. Tap does cut the stuff on a table saw but they use a special blade. I'm not sure a high speed anything would work on polycarbonate it doesnt like heat either. I quit making most of those pickups due to the problems with tapping it.....

Just an idea here but wouldnt a tile saw cut it good, the water would keep it cool and not do the melting thing and would be a smooth cut because they cut a lot finer, there would be less danger of binding up with melting and causing shrapnel to put eyes out.

Just a thought???

[jonson]

there is no prob using a table saw if you do it right. I quite happily cut .25 strips off 8' x 4' sheet and don't always bother to change the blade. the prob is the attack angle of the teeth doing the cutting. If you take a 10" blade and just feed plastic through the front edge of the blade it is cutting down into the material and knocking it about like a jack hammer so you have to drop the blade down. If this is not possible then lay several pieces of MDF or ply on top of the saw table so as the blade is now only showing 5/16 out of the table. The cutting now becomes a sliceing action cutting the underside first and elliminating any smash out.The correct blade to use would be a triple chip but standard saw blades do work but just dont give as good a finish.As with all plastic cutting hold the material down tight to stop any bounce, even on a band saw make sure there is a false board underneath so there is a much smaller gap under the saw to back the material up. This works with aluminum sheet as well allthough certain grades do tend to throw off fine chips which sting the arms but if set right on the waste will come off the blade as a long thin curl as if you were turning it on a lathe. The correct lubricant for Perspex cutting is white spirit though not sure what you guys call that in the States. Polycarbonate would only worry me if it had any form of lacquer put on it after machining as it then changes structure and can shatter. Happened to a lot of motorbike crash helmets over here back in the 60s. People painted them and they became useless (bloody dangerous)

[NightWinder]

No worries, as you can see, I'm replaning my construction!!LOL Funny, thats always the case.....seems it happens over there too. I feel better, LOL, it does'nt just happen to me!!!Glad to see you post some informative material. Well appreciated. Nice retirement spot by the way!!! Absolutly beautiful!! Thanks for sharing that brother!!

[EtLa]

the prob is the attack angle of the teeth doing the cutting.

You can also put the blade in reverse for cutting plastic.

[Satamax]

The solution for cuting drilling, tapping plastics, "negative or neutral rake angle" For bits, do it like this.

[NightWinder]

I Just recieved Multipul catalogs from Onsrud from jonson mentioning it. Their stuff is specifically designed for plastice, and different drills for different plastices too. Check them Out!! Their really on their game, and are very fast to send any cataloge you request for multipul materials....Loos like this company is top notch!.
www.onsrud.com - Thank Jonson for the hit>

[Satamax]

Nightwinder, for drill bits a litle diamond file or grinder is enough to flaten the lif for no rake angle. As showed in teh pic.

[NightWinder]

So, it would work essentially just as good? thiers are kicked back 60 degress, but you may be right....looking at how much on bit costs....holy shit

[NightWinder]

Forgot, and thier routing bits for Forbon....Did you stop by the site. All their stuff is relivant to the materials....just trying to decide which would be best for Forbon?(asking) In your opinion.

[jonson]

Not sure after 40yrs of running saw blades ranging from 1" to 24" diameter I would ever want to run a blade backwards. The teeth taper from front to back and top to bottom which is why you only sharpen the face not the sides and this applies to router cutters as well. The tooth cuts and then clears, so, running it backwards you are wedging your way through the material and gonna get one hell of a jam up one day. That's a dodgy shortcut. The angle I was refering to on a drill is not on the face it's the angle of the point. Make it longer so the drill point takes a lot longer to pass through the other side and prevents a lot of break out. Spur points work well( think you guys over ther call them brad points) but you still need to hold the work down tight to a backing board. Main thing I'm pushing here is safety but good clean work at the end as well.Nightwinder you wait till you get one of those cutters, they have a mirror finish and the swarff comes off the cutter like dust if you are set right.

[NightWinder]

I'm going for it!! Thinking I may need a few, spacifically a router bit for the forbon for rails, and a drill bit for clean precise holes. The Punch methods gets the job done, but is way too undersized, and when pushing the forbon over the mags are way to tight. Way much more time that it should be. I was thinking the PCD Roughing& finishing tool. Made for carbon fiber- G-10, and other fiberglass. Or the 63-600/900- all porpous for interior and perimeter routing(spiral flute)

[jonson]

Hi Nightwinder. can't comment on the pcd as not having a cnc router have left them alone. but for ruffing out would do the trick. Phone the guys at Onsrud up and talk as they won't bullshit you. The downcut left hand spiral will work and not sure if you are using a hand held router or you have it fixed which for small work is easy to do with half a sheet of plywood. If i'm working big (2" or 3") lumber then I use a big fast overhand router but for forbon and small plastic stuff just the router jigged in a cradle. Will take some pics and post. For the hell of it had f/all to do today so made a clone early Shatten winder out of PERSPEX!!! clean cut. clean drilled and clean tapped and nothing dodgy. Just need to take apart and sand and polish the edges. So can be done allthough took me 3hours and wouldn't make any money doing that as a production item.

[NightWinder]

I was thinking more simplistic. Making one hole at an end of the forbon, where the blade would end, and using the t-stop to keep it strait feeding it through the desired distance along the bar. using basically a drill press, but it is rather more a mini jewlers press, with about a 8,000 rpm max. Very simple. Did'nt mean to confuse with the cnc bit.....just thought the bit would work for the application better. I'll compile up some photos of the machine, and such and send you an e-mail later tonight. I think I will be calling them tomarro morning. Remember, they are about 3 hrs from me, so If they are really reponsive, I may take a trip down there with some precut Forbon. This is such High Quality stuff man.... Took 2 days to get a bunch of different catalogs from them. Really responsive. With all the materials, special tooling for them, I bet they would be more than happy to help.

[jonson]

I don't think you will be dissapointed with their cutters as it is "horses for courses". don't think your boys wen't into Iraq with water pistols. so it is the right tool for the job. My set up for milling forbon and small perspex items not costly and very very safe. Plus what can be done with plastics in a few hours with the protective film still on it. Finish it next sunday.