Moving QCTP shaft on a PM1127 lathe.. good or bad idea?

[Pcmaker]

I want to run this project first with you guys, the experts, before I decide to do anything.

I have a Precision Matthews PM1127 lathe. With the DRO that came pre-installed, I can't line up the cutting tool on the QCTP on the right side of the work piece if I'm holding it with a dead center. Even with the quill of the tailstock extended all the way, I'm about an inch short of the cutting tool being able to cut from the right side of the work piece. The set screw protecting the DRO scale is hitting the tailstock. I can't move the glass scale of the X axis DRO any closer.

The shaft of the QCTP is on the left side of the compound slide. I was thinking of making another shaft that will go closer to the center of the compound slide and mount the QCTP on there. I tried turning the compound to where the dial is on the left side, but it just gets in the way.

My plan is to drill and tap another shaft to where my cutting tool can finally turn a workpiece from all the way to the face of the work piece to the head stock when the work piece is supported by a dead or live center.. and also I don't have to stick out my tailstock quill all the way out and lose ridgidity.

Another issue is the stock QCTP shaft has a very loose tolerance. It's way off the diamater of the diamater of the QCTP and I don't like that for some reason, the shaft tapers to a much smaller size.. I don't understand why it's designed this way.

 

[ttabbal]

You can probably get the tool where you want it by rotating the compound a bit. Or the QCTP.

I don't think the post is threaded in. You will want to disassemble it and check. There might be interference under there as well if you move it.

The size difference is to allow space for the fastener that holds it down. There will be a little space in the middle not fully supported, but I doubt you will notice a difference. If tool rigidity is an issue, build a plinth.

 

[fradish]

What if you just rotate your QCTP so that one of the dovetails is on the right-hand side and put your tool holder there? You'll have to
turn the tool around in the holder, but it should get you further to the right (if I understand what you're getting at...)

 

[mattthemuppet2]

there's a whole bunch of stuff you can try before drilling a new hole in your compound

rotate the compound, rotate the QCTP and fit a holder on the right hand side, get a long nose live center or a half dead center, do most of the cut you want to do (but can't) with the work unsupported or further into the chuck or in a steady then finish the cut with it in a live center, do the same but make the end bit you can't reach sacrificial and cut it off after the rest of the work has been done. I've done pretty much all of these over the years, some work better than others, but you'll be able to figure out which one works best for you.

 

[Pcmaker]

I want to turn from the tail stock to the headstock without adding any more steps, also, won't having a super long live center make it less ridgid when turning? I'm afraid the cutting pressure will push the work and I'll end up with a tapered cut if the tailstock's quill support is overextended, making it less ridgid.

 

[pontiac428]

If you move the post (which I think is a good idea if it will be useful to you) and drill for a new mounting location, will you hit the lead screw on the compound slide with your post stud?

 

[mksj]

I do not advise relocating the tool post as the front off the tool post slide will hit the chuck/work. You can use an extended point (long nose or CNC) live or dead center that should give you a bit more distance from the tailstock and also use longer tool holders or move your current one so there is more distance between the work and the holder. You also want to make sure if using a live center, that the body diameter is small. I am assuming you have a MT2. You can turn a new tool post rod, most likely they use the same tool post that was used for the lantern tool post holder which has a step on the bottom. It looks to be two pieces from the diagram and retained with a screw from below (not threaded). You should be able to turn it as one piece with a large diameter.

2 MT Morse Taper Long Nose High Performance Heavy Duty CNC Live Center

www.shars.com

 

[Winegrower]

I say this not to be nasty, but having gone through something like this recently, perhaps you are now ready for a bigger more capable lathe.

 

[Pcmaker]

I use an MT3 live center. I guess I'll have to find one with an extended nose and has a smaller diameter body as my QCTP is hitting it when I get close

Also something I never thought of, if I move the QCTP, I'll lose compound slide travel

 

[mattthemuppet2]

I want to turn from the tail stock to the headstock without adding any more steps, also, won't having a super long live center make it less ridgid when turning? I'm afraid the cutting pressure will push the work and I'll end up with a tapered cut if the tailstock's quill support is overextended, making it less ridgid.

it's all a tradeoff - you pick the best approach and modify it depending on the need and project at the time.