Radius turning fixture

[Lindo]

Not sure where you live.
I am in Spain.
maybe some member could help out who lives locally to you.
But a simple project for as mill owner.

John

 

[kd0afk]

Thanks for the offer. I live California

 

[Noitoen]

Looking at the different radius cutter designs, couldn't the tangential tool design be adapted to this type of tool?

 

[Omnimill]

Looking at the different radius cutter designs, couldn't the tangential tool design be adapted to this type of tool?

Yes, should work fine. I would take the sharp corner off it though to give a smoother cut.

 

[Lindo]

Exactly,I use the largest radius tip DCMT available,as the radius is swung manually the sharper the tool point,the more unforgiving it can be to avoid leaving miniscule grooves.

John
Spain

 

[kd0afk]

Would an insert holder be sturdy enough if instead of having a cavity that the insert sits in, you would have four hardened pins holding the insert in place with a screw in the middle?

 

[Lindo]

I cannot see why it would not work.
provided they cleared the workpiece the tip is machining.
You could possibly get away with only 2 pins.
I believe you are taking this route as you have no milling machine.

Regards
John

 

[Omnimill]

Probably easier would be to use two triangular inserts back to back supporting each other? Accurate drilling of the two holes would be essential.

 

[Lindo]

Couple of points to consider,if I understand you correctly.

(a) Stacking inserts on top of one another could amount to several problems
of cracking,they can be quite brittle,and also it may be difficult to find the correct length TORX screw.The head of the screw and the tip counterbore are critical in retaining the tip in the correct place and rigidity.
(b) The DCMT (diamond shape) I have found to be better for sweeping into
a corner if you have a spigot on the end of the ball,chuck side.

John
Spain

 

[Omnimill]

Back to back, not one on top of another. Like this one but without material between them.

http://email.villagepress.com/pub/HSM/20101001/Images/3.jpg

http://www.projectsinmetal.com/wp-content/uploads/2009/01/radiusturner3.jpg

Agree about the clearance, that's why I chose the slim rhomboid shape insert for mine. I do intend to make another arm for mine though to use HSS tools.

 

[kd0afk]

I believe you are taking this route as you have no milling machine.

Regards
John

Yes, I've no milling machine and it sucks. Wish I could afford a Taig.

 

[Omnimill]

It does make life a little difficult not having a mill, especially if you have a small lathe. You don't need to worry about specialist Torx screws for the insert if you have difficulty sourcing them, standard countersunk socket screws work just fine with a little "modification" on the lathe!

 

[kd0afk]

What's screwed up is I can't find a job. I'm on disability but I'm allowed to earn $1100 more per month over my current income. If I could find work I could have a CNC Tormach in a few months. Without extra work, it'll take me a few years to save for one.
I can't even get a job washing dishes or cooking here in Fort Bragg, Ca. I'm really starting to hate the US immigration policy.

 

[Lindo]

Fully understand now.
The rear tip is only a support.Not sure why it's done,as I think it's impractical to cut anything from the operator side
of the machine.Again possibly to avoid milling the correct pocket shape.
If you check out Iscar,they have download PDF files of the tip geometry.
Also i do not like the cap head screws,buts that's me being politically correct.they look "Chinsy"
I like the TORX as it does not interfere with the swarf flow that a cap head could interrupt.
also how the screw acts like a glove,fitting nicely into the tip counterbores.
I have no friends in Sandvik to ask why they originally chose these screws.Somebody may answer this.
I believe the normal TORX thread is 2.5mm x .45mm pitch.Beware if tapping into steel,you will need lead,2nd and plug taps.
LMS may sell the screws,I will track down in my files where I purchased mine.
John
Spain.

 

[kd0afk]

I've asked Santa for a mill. I don't have any family left and all of my friends are homeless so I'm counting of the fat man to make Christmas not suck for a change.

 

[Omnimill]

I believe they place two tips on the tool to make both convex and concave cuts, at least that my understanding - sure I've seen a video somewhere. Agree about the cap head. I used a stainless steel countersunk socket screw on mine.

 

[kd0afk]

Yes, the two tips are for concave and convex cuts. I figured mounting the insert in the end of a piece of round bar and mounting the round bar in a piece of square stock at 90 degrees and the square stock would fit in the slot of the base. The slot on the base would be made with two pieces of square stock bolted onto the base.
The only problem is the socket for the insert.

 

[Omnimill]

Maybe you could hold the insert in place with a couple of pins and the screw?

 

[Lindo]

Understand now about the 2 tips.External/internal spheres.
basically you are emulating a DCMT type tip with 2 triangular tips.
As you know I use the DCMT type and if I need to do an internal sphere,just turn the dog leg tool holder 180 degrees.
As long as the end result works,thats great.IE the tip is the far side of spindle centerline.
Ref Milling machines check out Amadeal (Hugh),he sometimes has trade in's.
I have a Weiss 16,use it most days,it's 6 years old,never a problem.
Solid base,the head rotates up to 90 degrees each way,feed screw Z axis,DRO on the quill.
In my opinion,some of the mills are just drill presses with X and Y tables.
they seem to be not sturdy enough.
Just a thought,I know Santa may miss you out this year,maybe the little elves are working at Hugh's premises.
John http://cdn.homemodelenginemachinist.com/images/editor/smilie.gif

 

[Omnimill]

Yes, I've no milling machine and it sucks. Wish I could afford a Taig.

I'm really sorry I can't help you with this, it would not take very long on a mill. I moved house a few months ago and sadly I haven't been able to set up a workshop yet and my milling machine is in three pieces in the garage. I don't expect to have a usable workshop until at least next summer ...