4 way tool post on 12x36 woes..

[Daver]

This might sound stupid, but it's just different enough from my 7x10 to be really intimidating. It seems the 4way on my new to me 12x36 is actually too tall to use a 1/2" tool... Maybe.

The PO gave me some R8 cutting bits with the lathe. They measure out at .512" at the carbide tip. With that in the holder it places the cutter above the center of the spindle. Is that normal for the HF 12x36?

I see a couple options:
1. Buy a QCTP... But a BXA is just a bit out of reach $wise right this second...
2. I could clamp up the 4way in my micro mill and try to shave .015 from the bottom...not sure my micro is up to that...
3. I coul skip the pre-made bits and grind my own... Another skill to learn.
4. Could shim up some R6 bits, but they seem small on this machine.

any other ideas or comments for a newbie.

 

[kd4gij]

Can you post some Pic's of the tooling and the four way. The 4 way is probly for 1/4" -3/8" tools that you shim to hight. At least that is how mine works.

 

[LEEQ]

You have a mini mill, why not whittle out your own qctp? I can't wait to have my mill functional so I can make one for my lathe. Another thought is grinding the top of your carbide bits down while maintaining the same angle. Put the bit in your 4 way pointed at the tailstock and measure roughly how tall it is above a center. Grind a little much off the top of your bit and shim up to center. You could use the same idea and grind a layer from the bottom of the bit, but that's more surface and harder to keep flat. Angles of the carbide are not uber critical, just don't change too much.

 

[Daver]

You have a mini mill...

I have a micro mill, but I'm a little concerned that my skills are not sharp enough to make sure I get it right..

Do you have plans for a QCTP that a relative newbie could manage?

I could shim a 3/8" or 1/4" bit up, they just look like toys on this tool post. It is obviously made for 1/2" at least...

I'll try to get a pic up today.

 

[Splat]

FWIW I have read of guys using AXA sized QCTP on their 12x36's so I guess the BXA is too big depending upon the machine.

 

[LEEQ]

I have a micro mill, but I'm a little concerned that my skills are not sharp enough to make sure I get it right..

Do you have plans for a QCTP that a relative newbie could manage?

I could shim a 3/8" or 1/4" bit up, they just look like toys on this tool post. It is obviously made for 1/2" at least...

I'll try to get a pic up today.

Shimming smaller tools look like your fastest route to chip making for sure. As to the project I would go for it. We say at work if you're not f'ing up you're not doing anything. Same for learning, nothing ventured, nothing gained. I know there are plans around here, you might check in articles and downloads. I once googled it and got a lot of different plans also. Good luck. Oh, if you have a hard time locating shim stock, I bought a set of automotive feelers for $3. Works great.

 

[stern]

I too would be very interested in any plans anyone has for a QCTP for my PM1027, as I hate the shimming and I would prefer to use bitter tools in the holder. I have always wanted one but the price and knowing which will fit has made me forget the idea. After seeing some post about making tool holders and actually making a boring bar one, I really would like to make one that will hold my tools which have all been adjusted to the proper height.

 

[jpfabricator]

I would measure how much to take off the bottom of the tool post and mill it. When your done you can always take a light facing cut on the minilathe. once thats done you can always use 1/2" tooling, and shim for the rest.
JP

 

[LEEQ]

I too would be very interested in any plans anyone has for a QCTP for my PM1027, as I hate the shimming and I would prefer to use bitter tools in the holder. I have always wanted one but the price and knowing which will fit has made me forget the idea. After seeing some post about making tool holders and actually making a boring bar one, I really would like to make one that will hold my tools which have all been adjusted to the proper height.

I just went to yahoo and typed in qctp. Qctp plans popped up as an option. I clicked it and all different kinds of plans popped up with a variety of difficulty. There is something out there just waiting for you to see and make your own. you might need to change scale of some parts, but no step for a stepper. I can't decide which one to do myself, when mill is finished I'll pick one and dive in. Good luck

- - - Updated - - -

Something I noticed about prefab Chinese carbide bits, is they do not sit the same height from bit to bit. I have two sets and no two bits cut at the same height. If you don't grind bits or use qctp, shimming will be required. Something to consider when determining the depth of that facing cut. You will also probably lose the detents set at 90 degrees if you cut the bottom of the fourway.

 

[pdentrem]

You can shim the 4-way tool post higher and use an endmill in the spindle to machine the bottom surface of the tool slot. That way you are lowering the tool slot as you feed the tool post across the front of the end mill. Feed from the back towards you that way the backlash is removed.
You will still have to shim no matter what you do. It is the nature of the beast.
The pictures shows the start position which is the tool post is behind the end mill further from you, and the second shows the finishing position with the tool post closer to you.
Pierre