Setup for steel plate??

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negatronix

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Hi all! Total noobie here... go easy please!

My question- I need to cut some 3/16 & 3/8 CR plate into shapes, that will later be welded into a spindle. Should the material be clamped into a vise so it is standing on edge, and milled along the top surface, or mounted flat and milled along an edge much like one would use a jigsaw to cut a shape out of wood...or so to speak.

There are a few holes in each part, which would allow me to make a few spacers, and bolt the part to the table as well. This would hold the part parallel to the table, as well as hold it up off the table.

I am a complete noob, and want to ask questions to avoid getting hurt, avoid unnecessary tool damage, and of course.. I don't want to pick up any bad habits. I will have lots of flat parts to make so any good advice on setting up to cut plate into irregular shapes will be a huge help to me.

Thanks in advance!
-Kory
 
negatronix said:
Hi all! Total noobie here... go easy please!

My question- I need to cut some 3/16 & 3/8 CR plate into shapes, that will later be welded into a spindle. Should the material be clamped into a vise so it is standing on edge, and milled along the top surface, or mounted flat and milled along an edge much like one would use a jigsaw to cut a shape out of wood...or so to speak.

There are a few holes in each part, which would allow me to make a few spacers, and bolt the part to the table as well. This would hold the part parallel to the table, as well as hold it up off the table.

I am a complete noob, and want to ask questions to avoid getting hurt, avoid unnecessary tool damage, and of course.. I don't want to pick up any bad habits. I will have lots of flat parts to make so any good advice on setting up to cut plate into irregular shapes will be a huge help to me.

Thanks in advance!
-Kory
Click to expand...

Cutting steel plate into shapes on-edge most likely means alot of material will be cantilevered into space and therefore be much less rigid than it would be if held horizontally in a vice or fixture.

Generally not something you want to do unless you have no choice.

If there are holes in it and you can use them to mount as you describe without interfering with your toolpath, by all means do so. You still need to make sure there are enough holes to reduce vibration enough to where your tool wont be ringing the plate and causing bad finish and tool damage. This is where hold downs come in. You basically pinch the part to the bed or a sacrificial plate of something like aluminum, which gets bolted to the bed.

A good habit is to make a fixture plate that bolts to the bed, and has threaded holes you can mount the workpiece to either using its existing holes and/or hold downs.

Next best is a vise but that depends on how big your piece is and how well you can hold it in a vise.
 
+1 what spaceman_spiff said.

If am able, I will always choose bolting or clamping the work flat to the table, the vice or angle plates is the second choice. Many times I will use particle board, plywood, or MDF under the work as a spacer when profiling. If I really need height accuracy, I will use aluminum under as a spacer, but MDF is pretty flat. If the holes in the work won't line up with the table T-slots, then I bolt the spacer down to the table T-slots with flat head capscrews then screw the work to the spacer with wood screws or capscrews depending on the spacer material. I have been known to put screw inserts or wood type t-nuts in wood type spacers to provide a threaded hole. Or sometimes even drill & tap plywood or MDF.
 
also it should be noted that machining steel plate is not the most forgiving thing for someone new to machining..if you havent already I'd post up detailed pics showing what you are trying to do so we can give you more assistance with getting it done
 
Thanks for the replys! I will get some pics up as soon as I get to a starting point. I am still ordering tooling, and figuring out some other things I'll need... Im on a very tight budget.

I have a lot of scrap MDF, so I'll be exploring that direction first.

I'd like to make a plate that I can mount a piece of MDF or aluminum into that mounts to a rotary table. That seems like a very practical way to do things with a minimal amount of part removal, and reclamping. What do you guys think?

-Kory
 
I would lay the plate flat either in a vise or with stand-offs bolted down to the table. I also prefer to use a roughing end mill for all but a finish pass. It cuts much faster, and the chips are small and not as razor sharp as with a normal end mill. I have a 3/4" TiN coated roughing mill that works particularly well for this.

I've been working on a couple of projects this week where I'm milling 1/2" steel plate into various shapes as well. One on a rotary table, the other fixed to the mill table. I'm running the spindle at about 780 Rpm, and can easily take up to a .300 pass on the half inch thick plate.

GG
 
For me, Milling steel on a hobby-mill became a challenge due to chatter. It was 1045 and I did get a system which I could cut and get my stuff done. What it took was a lot of patience and trial/error and a few broken end mills. Clamping it down flat was the only way. Wondering what type of Mill you'll be using? Experiment on a few pieces first btw. If I use a 1/4 to 3/8 end mill and such it's pretty easy. Slow but easy. Get into the .5 endmills and it's a chatter-happy event until you find that 1 sweet-spot for your setup.
 
I need to order some roughers. I only used one on one short deal but man it makes it easy. If you have a small bench or small knee a rougher will let you feed it. How much is relative but feed none the less.

Far as a plate on the rotab that should be easy enough. Just sink your screws flush with the top of the plate. but in line with the 4 slots. Then screw into T nuts. In theory you could make the plate as large as you want so long as it clears the plates/handle. Thats in theory. More over hang unsupported will reflect rigidity in relation to plate thickness I would suppose. Rather the further it sticks out, the thicker you want the plate to be. What equation you would use to find that relation, I have no idea ahaha
 
Yeah- I keep meaning to order a 5/16 or 3/8 rougher myself.. PST has free shipping this month if I recall. Headin' there now. Thanks! Great idea.
 
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