webgeek
Plastic
- Joined
- Jan 26, 2010
- Location
- Kansas, USA
Hi all; I've moved on from my tiny import CNC mill I converted myself to a real (though still a budget model) 3 axis CNC machine with 24" x 15" table travel. I'm a total amateur at CNC machining and have slowly been learning all the ins and outs as I go. I think I've gotten to be reasonably good at the few operations I need to make my parts but I recognize that I have a very long ways to go. For reference, I sell small parts to people making radio-controlled four to eight rotor helicopters (quadcopters).
With my previous machine, I was only able to make one or two parts at a time and it took forever to machine much at all. This new machine is both much larger and faster so I want to leverage that all I can. The problem is, I'm not sure the best way to do that and I'm hoping you guys can point me in the right direction.
I've attached an image that represents the type of parts I make currently - basically 2d profiles around the whole perimeter with some drilling and a little bit of pocketing to create the retaining channels. The material is either .25" or .09" - I'm looking for advice on how to machine these style of parts as quickly as possible - basically set up the machine to create a ton of them and come back in a few hours to find them all done.
I've tried doing a variety of things on my smaller machine and some things work well but none of them seem to scale up effectively. To date I've done this:
1) Drilled a series of mounting holes in a piece of raw stock. These holes corresponded to the design so it worked out nicely. I then created a fixture plate out of 1/2" aluminum and used shoulder bolts to pin the material to the fixture plate. Finally, I aligned and touched off the plate and let the machine rip. The problem is the shoulder bolts are quite small (4-40) as the parts are tiny and the bolts work themselves loose while machining the part. This has broken bits, lost steps, etc. All bad. Obviously I could use a thread locker but this would dramatically slow down set up. It seems there should be a better way.
2) Simply cut the part and let it pop itself loose when done, about 1 in 3 or 4 times the "popping loose" nicks the part bad enough that I can't use it. I know this is TERRIBLE but it is fast and simple and seems to work with these tiny parts. The issue I have with this approach is that as the material gets thinner and larger (to cut multiple parts at once), it gets hard to clamp it properly so that it won't bow up in the middle. These are low precision parts (0.01" is fine) so a tiny bit of bow is fine, but it causes other problems like the bit lifting the material and such and that is where I run into problems.
So what's the trick for parts like this? I've heard carpet tape works well and I can do #2, just with added tape. I've tried that a bit and the results are interesting but you still need to clamp the material as the tape alone isn't enough to keep the material from sliding while being cut. Since the tape is a little spongy, things have a tendency to bow up on you even more. Also, once the parts are machined, it's VERY hard to remove them from the tape itself. Things really get stuck together. Is there a trick to the tape?
Should I go a totally different direction on this? Thanks much in advance!
-Mike
With my previous machine, I was only able to make one or two parts at a time and it took forever to machine much at all. This new machine is both much larger and faster so I want to leverage that all I can. The problem is, I'm not sure the best way to do that and I'm hoping you guys can point me in the right direction.
I've attached an image that represents the type of parts I make currently - basically 2d profiles around the whole perimeter with some drilling and a little bit of pocketing to create the retaining channels. The material is either .25" or .09" - I'm looking for advice on how to machine these style of parts as quickly as possible - basically set up the machine to create a ton of them and come back in a few hours to find them all done.
I've tried doing a variety of things on my smaller machine and some things work well but none of them seem to scale up effectively. To date I've done this:
1) Drilled a series of mounting holes in a piece of raw stock. These holes corresponded to the design so it worked out nicely. I then created a fixture plate out of 1/2" aluminum and used shoulder bolts to pin the material to the fixture plate. Finally, I aligned and touched off the plate and let the machine rip. The problem is the shoulder bolts are quite small (4-40) as the parts are tiny and the bolts work themselves loose while machining the part. This has broken bits, lost steps, etc. All bad. Obviously I could use a thread locker but this would dramatically slow down set up. It seems there should be a better way.
2) Simply cut the part and let it pop itself loose when done, about 1 in 3 or 4 times the "popping loose" nicks the part bad enough that I can't use it. I know this is TERRIBLE but it is fast and simple and seems to work with these tiny parts. The issue I have with this approach is that as the material gets thinner and larger (to cut multiple parts at once), it gets hard to clamp it properly so that it won't bow up in the middle. These are low precision parts (0.01" is fine) so a tiny bit of bow is fine, but it causes other problems like the bit lifting the material and such and that is where I run into problems.
So what's the trick for parts like this? I've heard carpet tape works well and I can do #2, just with added tape. I've tried that a bit and the results are interesting but you still need to clamp the material as the tape alone isn't enough to keep the material from sliding while being cut. Since the tape is a little spongy, things have a tendency to bow up on you even more. Also, once the parts are machined, it's VERY hard to remove them from the tape itself. Things really get stuck together. Is there a trick to the tape?
Should I go a totally different direction on this? Thanks much in advance!
-Mike
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