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if you can't go up in rpms the only option you have is to slow your feed down.
I am assuming your tried better brands of tooling.
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What up guys,
How small of a ball nose end mill have you guys used before. Also, what kind of machine and spindle speed did you use?
Right now I have a part that is bronze, 1.950"L x .750"H x .482"H. I'm down to the smallest endmill I can consistently use (.031). I'm still having trouble getting in between everything. I have some .016 Ballnose endmills, but I have the worst time with these breaking. All the formulas I use show me needing a RPM of like 70,000. My machine will come no where close to that. What can I do?
The "Z" is silent
if you can't go up in rpms the only option you have is to slow your feed down.
I am assuming your tried better brands of tooling.
I use .031 Ball for engraving and have a .015 I've been to scared to use (haven't NEEDED to learn to break it yet).
I'm only able to run 4000 rpm and just run it slower. I think g wizard told me to run at 3 ipm or something insanely slow like that. I run it at 5ipm and haven't broken one yet, but that is only engraving.
buyG wizard our at least get the free trial. its a great tool. you can set your max rpm (our virtually any other parameter) and it will calculate the speeds for you. if you are using small em make sure you enter all the info (especially tool stick out) so it can calculate tool deflection and let u step up from "safe" till you break one then back off a 25% on the feed and you should be good to go with the max realistic speed.
I have found g wizard to work great on my little toy cnc if I use 75% of their (aggressive) setting.
if you do a lot of this work you should bite the bullet and get a high speed spindle that bolts on to the head. doesn't take very many cuts at 20 ipm vs 3ipm to pay for a high speed spindle.
not sure what your machine is but tormach had several that can be made to fit most machines.
don't bother trying to mount a dremel... ask me how I knoweven after rigging a mount for just the "tail" wand with the dremel suspended from the ceiling its WAY TO off balanced.
duplicate post
Originally Posted by PriddyShiddy
That's about what I run my .03125 ball nose em at.
The "Z" is silent
For 3d, it's important to get the bulk of the material out of the way first, before starting to use your smallest tools to get the detail. Generally, you can use a much larger tool to do this roughing pass, and most CAM programs will let you specify a skin thickness over the finished surface for the smaller tool to remove.
You don't say what your spindle RPM is, but I've been able to use a 1/32" tool pretty effectively with a 10k RPM spindle (but not fast). If yours is much slower than that, your feedrates are slowed down to a crawl, since there's a certain maximum chipload that each flute can remove as it goes around before it can proceed, and if you exceed that the tool will break.
Mounting a faster tool in your spindle might be an alternative for you, if you're using a quill-driven Z axis. There are "spindle speeders" available that will boost your RPMs by a factor of 2 or 3. If you need still more speed, there are air turbine driven accessories that go a lot faster. If your whole head is going up and down instead of a quill, then it's a lot easier to mount an auxilliary spindle outboard.
Andrew Werby
ComputerSculpture.com — Home Page for Discount Hardware & Software
Here is a picture of what I'm working on. The Solidworks model is not exactly what it's got to look like. It's just got to be close enough to stamp the logo in a bar of soap. The letters are .020" tall.
The "Z" is silent
I use a .094 ball nose to kinda rough in the shape and then go back with the .031. My spindle also only turns 8K RPM. When this machine was purchased it was not intended on making such small parts but I don't really have a say in the matter on what we build or don't build. I'm just stuck doing the best I can do with what I have. I'm using a Hyundai Kia vx-500 btw.
The "Z" is silent
Our slowest spindle for doing this kind of work is 10K. Most of the small stuff is done on our 20K or 50K spindles. .008" diameter tools is not uncommon here.
I see, looks like I need to get another machine. Do you have any recommendations? It's possible I could get a new machine with a high speed spindle in the 10k-50k rpm range if the machine was small enough. I'm thinking something like a 10" x 20" table. I know very little when it comes to brands and terminology with these machines.
The "Z" is silent
You can get a special spindle that goes in your regular spindle and has very high RPM's.
Air spindles are cheaper, but use a lot of air - they come in electric too. I've seen 50,000RPMs.
I don't agree that you need another machine. Just go slower feed like the others recommend.
Another thing that is critical in running these tiny tools is run out. Keep on changing collets untill you get one that is, at most, a couple of tenths out. Sometimes you can rotate the collet in the nut to change the run out.
Critical!
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