Critique my setup

[Bill S]

Critique my setup

I’m making plates for a finger brake I am working on and I am not quite sure of this setup. Could any of the more experienced members give me a heads up if anything looks wrong? I want to put a 52-degree (exact angle within a degree is not critical) bevel on the fingerplates and the only bit I have is a 60-degree dovetail. I have an alum extrusion with a flange on one side that I mounted as a stop for the one side of the piece. I had to elevate it with 123 blocks to get a good height for the bit, and indicated the rear flange to within a thou. I then used a parallel to raise the front of the piece to get my proper angle for the cut. To keep the parallel from flopping about I ran screws with large washers into the extrusion. The holds down clamps are the items that are a bit of a concern, because they are on an angle. I am only taking light cuts and all seems well, but I thought it might be a good idea to get some feedback on it. Please be brutal, I am a retired Tin Knocker and have no formal machine training, only what I have picked up on the forum, but I do want to learn.

One other thing, the chips I am getting are superfine, almost like dust. I am running a light cut (.030”) fairly high spindle speed and a slow feed rate. Is that typical?

Thanks,
Bill

 

[te_gui]

Setup looks OK to me, I'm wondering based on your chips if you don't have some cast aluminum tooling plate there rather then extruded material for your stock. Either way its coming off.

Brian

 

[wackyvorlon]

Looks good, the step-block clamps might mar the piece of aluminum, but other than that it's fine. One thing I'll do sometimes with a setup is to try pulling the part. I grab it and pull. If I can move it, it will move during milling. It occurs to me that if you really wanted, you could put jackscrews between the clamps and the plate. That would take up the tilt fine.

 

[Bernd]

Bill,

Looks like you've got things pretty well clamped down. I'd say you could go a bit heavier on the cut like say .050" and a bit faster on the feed. Listen for vibration as you cut.

Let us know how you made out.

And remember to tighten down those clamps good, but not to the point of were you bend things.

Bernd

 

[Mike N]

I would not clamp a thin piece of aluminum without support directly under the clamp. I would think that your part would move. If your chips look like dust you don't have enough chip load (Faster feed rate or Slower cutter speed) also your cutter will get dull faster. With that setup you can't really push it very hard. I have a large sine plate that I made for milling angles like that, I would use a 2 flute end mill for aluminum, instead of an expensive dovetail cutter. If it works how can I criticise your setup? I have been in the Tool & Die business for 36 years & I have launched a few parts in my day! I like this hobby because it teaches us problem solving skills, especially when it comes to machining a rough casting with no good way to hang onto the part to get started. Good luck!

 

[Bill S]

Thanks for the advise Guys! The alum is 1/2" and doesn't seem to flex given the short length and for it's intended use marring isn't a problem. Boy I love this forum!

Bill

 

[DickDastardly40]

Bill,

I'm with the others seeing nothing glaringly wrong with your set up.

Does the head on you mill swivel, if so you could set that to the desired angle, put the job vertically in a vice and cut the chamfer with the side of a normal milling cutter (fast helix if available for aluminium). If the Y feed is not enough you could do a portion then slide the job in the vice without moving X to take some more off. Because the head is angled hopefully the job will be further to the side and wouldn't foul on the mill column.

Just a thought.

Al

 

[Bill S]

Update

The pieces are done and it went pretty well. I found I could speed the process up considerably by precutting the bulk of the material off of the bevel on my wood band saw. A 4tpi skip tooth blade makes short work on non-ferrous material. Because of the setup I used I found I had to be very careful in tightening the clamps evenly so as not to have one end higher (lesson one: ½” alum does flex enough to change the setting) and I did have one piece start to come loose (lesson two: the piece should be supported better underneath so the clamp could have been cranked better) No damage was done and I was able to finish. Mike, I don't have a sine plate, but something along those line would have worked much much better for me. Dick, Unfortunately the head does not swivel on my mill.

Bill