I’m having trouble milling parts out of abs sheet. I’m using an OFlute bit, and the initial milling goes ok, roughly 1.5mm/pass on 6mm sheet. The issue I’m having is that the bit seems to get stuck, skips some steps and then ruins the cut. I have a feeling this is related to holding down the part (currently using doubles sided tape). Any suggestions of how to get the sheet secure on an MDF spoil?
This picture is an idea of what I’m cutting. Not the one I was looking for but gives the idea. It seems like in between the tape downs the plastic wants to lift. Is it climb milling? What’s the ideal way to do this?
An upcut mill will lift the work when it can. A straight flute bit or downcut will alleviate the problem. Either that or you need a lot more hold down.
Climb or conventional milling will not make a significant difference with this problem.
The stuck part caught my attention. Somewhere I have a short video where I was using double sided tape used for wood. Worked great until the bit cut into it. Gummed up the router bit, grabbed the strip of wood I was milling and transformed it into a missile. Lucky it launched away from me. I don’t use double sided tape when I cut though any material now. For flexible plastics I stick to vacuum pucks. Easy to make and level.
yes, it could have to do with glue/tape on the bit. What seems to happen is in between the tape, the bit lifts the plastic up, maybe because of the tape. I can’t remember correctly but I think it only tends to happen once I am through the material.
Vacuum pucks sound amazing. I was going to cut grooves into my spoilboard to put a vacuum behind, but if there’s a way without needing to do that I am in.
Ok, here are some pics of some of the “fixture pucks” I like using. I set up the basic sketch in Freecad using parametric spreadsheet. Quick and easy to change sizes. I tried the 3d printed one, but like using wood. Bolt it to my table and do a light plane of the surface to level if I need. I mark each one on its location when using more than one. Makes it easy to set back up later. I just use 1/4 inch foam window seal, instead of O-rings. Connect with 1/4 inch plastic airlines
The yellow one is not mine, Got it online, works nice for PC boards. I haven’t been able to find it again online. It was quite a few years ago.
Have you used these on full or half sheet? My parts are rather large and I’d consider making a few of these if that works, but I’d be worried about sag between hold downs. I’ve been considering grooving the spoil board itself to hook up a vac and maybe that’s the best way, but since I do both wood and plastic it might be nice to keep the spoil as is. Perhaps make large pucks evenly spaced? What works for you?
That’s why I like these. In your case I would use pine or any scrap wood you have. Cut in whatever size that fits in your pattern, fasten done in the area your cutting. Surface cut level and cut your vacuum channel. You may want to add a couple of long rectangular pucks along the long side so that the sheet doesn’t move when you cut your object out. You will get a better feel about how much support you will need for your material. Will be a lot less than the whole surface. Biggest area I have done is 24x24 inch. 1/16 thick. I used 3 1/2x4 boards about 24inch cut a 2 by 20 vacuum slot in 2 of them ,one on each side. Blank board in middle just for support.
