PM1236 Cross Slide Lock Access

verbotenwhisky

H-M Supporter - Gold Member
H-M Supporter Gold Member
Joined
Dec 18, 2022
Messages
2,623
I though about posting this on the what did you make in your shop today thread but decided to give it its own post to make it easier to see/find for others working on simlar issues.

Well I had been running the lathe without the use of the cross slide lock but needed it on a regular basis. At issue was the DRO scale mounted on the back of the cross slide which covered the lock up and I really wasn't in a hurry to take the scales off.

Well as normally happens I broke something, as a side note I really do find that the only issue I have with the imported machines is fit and finish; so, in this case I stripped one of the t-bolt holding the compound (Partially my fault and partially fit and finish issue). I had really not liked the fact that I could see the first thread of the nuts on these t-bolts when they were tightened down, the design/engineering rule is when the nut is tightened down there should be at least 2 threads visible above the top of the nut which ensures full engagement and proper loading of threads, mine were likely only utilizing 75 or 80% of the required threads.

So, on my PM1236 to remove the compound bolts, due to a poorly placed access hole you have to remove the cross slide and in doing so I had to pull the scales, oh look an opportunity to fix the cross slide lock access issue..... :confused: I had discussed the issue with PM at one time and they recognized this as an issue and said the solution was to space the scale out; but, once I had the thing apart it dawned on me that there is a 3/8" thick Aluminum bar spacing the scale out already so it looked like opportunity to avoid reducing the reach of my tail stock further so I marked the location of the lock on the piece and milled out a section leaving .060" on the bottom and .010" for the actual scale to rest on. Next I drilled a hole in the bottom leg so any oil accumulating in it could drain.

I pulled the dog nosed set screw and found it to be 5mm long and realized that when run in far enough to engage the gib and lock the cross slide an Allen key long enough to engage it would not fit into the slot I had milled. I researched the screw and located a dog nosed set screw that was 14mm long and when threaded into the cross slide it was both at the face to the casting and touching the gib, this works well, I ground an allen key to .300 long and it slides into the milled slot and can be inserted into the screw and a 1/4 turn takes it from loose to locked which means the top of the screw is still accessible with the modified key.

All is back together and works well, I hope this helps others with a similar issue.

Cross Slide Lock.jpg
 
@davidpbest beat me to it, but since my Mini-Lathe didn't have cross slide or compound locks I added them a couple of years ago, originally using small lever handles like this one on the compound:

20240107 Compound Lock.jpeg

Drilled & tapped (M4) extra gib screw holes, tucked a 3mm BB into the holes (to get point contact on the gibs) then screwed in the clamping levers.

However, when I modified & relocated the carriage lock I replaced the lever on the cross slide with a hex head bolt (red oval) to clear the carriage lock assembly:

20240107 Cross Slide Lock Annotated.jpeg

There's not a lot of extra space on a Mini-Lathe, so you have to make do (the X-Axis DRO is under the cover/scale support on the end of the cross slide).
 
The problem with anything on the left (headstock/spindle/chuck) side of the carriage is access when you are close to the headstock: that's why I moved the carriage lock to the right/tailstock side.
I tried the lock on the head stock side and found it to be a bad idea because you cannot easily access it when you need to retract the cross slide.

Yea, that locking grub screw is poorly positioned. Did you consider replacing the grub screw with a hex-head bolt of the same size so you could articulate it with an open-end wrench from above?
View attachment 502245 View attachment 502244
I had looked at doing it that way but on the PM1236 the tailstock reach is limited by the scale and the hex head would have required additional set back for the scale, I made a short allen key, shown in the photo when allows good access with the longer grub screw.

Is your scale above the reader?
 
Is your scale above the reader?
Some details on my DRO installs were posted here several years ago, but can also be reviewed in detail at this link. Yes, the scale on my cross slide DRO faces downward, the encoder faces upward, and the entire system is encapsulated in surrounding thick aluminum protection. I have never liked the idea of putting the cross slide DRO scale/encoder on the chuck-side of the carriage where it is more easily damaged. Personal preference for sure.
 
Some details on my DRO installs were posted here several years ago, but can also be reviewed in detail at this link. Yes, the scale on my cross slide DRO faces downward, the encoder faces upward, and the entire system is encapsulated in surrounding thick aluminum protection. I have never liked the idea of putting the cross slide DRO scale/encoder on the chuck-side of the carriage where it is more easily damaged. Personal preference for sure.
A misunderstanding, When I refered to the Chuck side installation I was commenting on ChazzC's comment. I didn't mean the scale was on the chuck side, I attempted using a cross slide lock that I installed on the chuck side to avoid the need to disassemble the scale which is on the tailstock side of the cross slide, I had seen the idea on the forum and it looked good but it was not.
 
Some details on my DRO installs were posted here several years ago, but can also be reviewed in detail at this link. Yes, the scale on my cross slide DRO faces downward, the encoder faces upward, and the entire system is encapsulated in surrounding thick aluminum protection. I have never liked the idea of putting the cross slide DRO scale/encoder on the chuck-side of the carriage where it is more easily damaged. Personal preference for sure.
You have a great setup David, currious, where did you find the drag chain, I would like to make that modification to my Lathe. And second question, for the hex head cap screws securing your compound to the cross slide, did the lathe come that way or is that one of your mods?
 
You have a great setup David, currious, where did you find the drag chain, I would like to make that modification to my Lathe. And second question, for the hex head cap screws securing your compound to the cross slide, did the lathe come that way or is that one of your mods?
At the link I provided above, each photo has an accompanying description if you just click on the image, and in the description with this image you will find details on the drag chain I used in the description. I replaced all the fasteners on my 1340 with higher grade components when I stripped down the machine for a new robust body filler and paint and made tons of additional modifications. The hex-head screw was one tiny detail in the overall DRO design process. Three full pages of details of the entire build are here.

A misunderstanding, When I refered to the Chuck side installation I was commenting on ChazzC's comment. I didn't mean the scale was on the chuck side, I attempted using a cross slide lock that I installed on the chuck side to avoid the need to disassemble the scale which is on the tailstock side of the cross slide, I had seen the idea on the forum and it looked good but it was not.
No misunderstanding - others commented on putting it in the chuck side of the carriage.
 
Back
Top