Need info about lathe bits

Pooh_Bear · Jan 24, 2006

Ok, here is what I want to do.
A shaper cuts on the push stroke only.
You let the bit move across the material,
then move over slightly and make another cut.
I want to use a parting bit, make one cut across the material,
then move the bit down slightly and run it across again.
Repeat this until I cut thru the metal.
I could put together a machine that will cut up to 50inches wide.

Yes it would be easy to cut metal with a o/a torch or plasma cutter.
But I have neither. And I could build the machine I am thinking of.

And add a rotary table and I could cut perfect circles.

These are just some ideas.

Pooh Bear

Bigbear · Jan 24, 2006

I'm with ya Brother Bear, sorta like a saw, with just one tooth. If I understand this, you want to drag or push a cutter across thin metal and remove a small amount of material with each pass. It should work, I think you might want a V type cutter, unless your cut off tool is very thin. You can buy cut off tool blanks that would be easy to work with. BEAR

scott_vt · Jan 24, 2006

Pooh Bear,
With the proper clearances on a tool you could cut most anything. If you could tell me what your trying to cut I might be able to help. I have been in the trade as a toolmaker/modelmaker all my life and have ran and operated various types of machinery. We still use HSS bits for most work on are Hardinge lathes in our toolroom. Carbide is great for those tougher alloys, but HSS is still the tool of choice for most lathe jobs. We grind our own tools by hand or with the aid of a tool bit grinding fixture on one of our surface grinders. Also, parting bits or cutoff bits can be bought as thin as 3/32 for our Hardinge lathes.

So, what type of material, thickness etc are you trying to part?
I would be happy to help in any way.

scotty

Pooh_Bear · Jan 24, 2006

The thickness would range from from 0 to 1 inch.
Although I think I would only be cutting 3/32 to 5/16 stuff.
But the capability would be up to an inch thick.

Only money I can put into this project is a few dollars for a HSS cutter.
Everything else has to be scrounged from scrap I can find.

Pooh Bear

scott_vt · Jan 24, 2006

OK,
It sounds like your trying to design something thats similar to a shaper, that you can cut larger sheet stock to specific sizes. Im sure by now you have an idea how your going to hold this sheets stock in position while you are cutting it. It will obviously need to be fastened securely while you are sending a single point tool across the surface. What are you planning to use to move the tool, hydraulic cylinder?
Also another thing to keep in mind, you wont be able to go too thin on your tool bit because of deflection, especially in thicker material. Just wanted to throw a couple of things put there for you to think about if you havent already. /forums/images/graemlins/grin.gif

scotty

Pooh_Bear · Jan 24, 2006

I thought about a hydraulic cylinder,
And that would probably work great.
But then I would need to find a cylinder.
I was thinking more along the lines of just using a lead screw.
I used to run a CNC router that used lead screws to move the carriage.
The router moved in 3 axis, x,y,z I only want to move in 2, x,z.
Although if I had a plasma cutter I would want to move x,y,z
and use the plasma cutter to cut whatever shapes I wanted.
Add a couple of step motors and make it CNC.

For stuff thinner than 3/32 I would cut it with something else.
I want to work mainly with 1/8, 3/16, and 1/4 inch stuff.

To hold it while cutting just clamp it to the table.
A few clamps here and there should work fine.

I saw something like this years ago only it used an o/a torch to cut with.
The torch rode on a carriage and cut the steel as it moved across it.
It cut extremely accurately and straight.
I want to do the same thing, but use a cutter bit.

Pooh Bear

scott_vt · Jan 25, 2006

Well, I like the plasma cutter much better than a single point tool. The thing you need to remember with constructing something that will be used along the lines of a shaper is that the machine frame needs to be quite stout. I mean really strong. Also, if you are going to drive a carriage using a lead screw, preferably acme thread, that lead screw needs to be quite substantial also. Im sure you have seen a shaper, and how it is constructed, comparable to a tank /forums/images/graemlins/grin.gif

scotty

Pooh_Bear · Jan 25, 2006

I like the plasma cutter too.
But if I had one of them I wouldn't need to build this contraption.

We had a shaper in the shop in high school.
I don't think a tank would've stood a chance against it.
Specially if you dropped it on the tank.
That hulk of a machine had to weigh a million pounds.

Pooh Bear

HomeBrew2 · Jan 25, 2006

Ok, I'll bite. Hows come you can't just use the old trusty electric jig saw? The saws are cheap (store sales, swap meets, garage sales) and good bi-metal blades are cheap. Straight lines can be controlled with a rip fence or angle iron guide and radii can done precisely with an easy to make pivoting swing arm. It has worked well for me over the years /forums/images/graemlins/grin.gif
Cheers!