# I Cut in to the Compound on my Lathe



## erikmannie (Mar 3, 2021)

I bought this PM-1660TL new 4 months ago.

This was obviously 100% my fault. I had the compound set at 37 1/2°. My plan was to turn, groove & then cut the taper.

The workpiece was 4” pipe. As I was turning (on power feed), the pipe rotating at 180 RPM collided with the compound.

Precision Matthews has replacement parts for all their machines. This damage is only cosmetic, so there is no emergency. The gibs are probably hand fit, so I will have to consider that.


----------



## mattthemuppet2 (Mar 3, 2021)

don't worry, it'll get plenty more battle scars as time goes one - they show that you've been using it and learning on it! As long as it doesn't affect function it doesn't matter, it's a tool after all.

If you want to make it a feature, gently engrave the date next to it


----------



## stupoty (Mar 3, 2021)

You dun dinged it now  

Maybe give it a file to make it a rounded to avoid stress risers and cracking and cutting figures on sharp bits.



Stu


----------



## Superburban (Mar 3, 2021)

Roud it out with a carbide burr, and then add one to the other side. Then engrave a line across between the two. it will look factory done then.

When people ask about the line, just say they put it there to remind you to watch for a collision.


----------



## erikmannie (Mar 3, 2021)

You guys made suggestions that I had not considered.

The most economical choice would be to get rid of the stress risers.

I do rotate my compound a lot. I could look to see where my thumb & fingers are when I do that. Maybe reliefs for fingers & thumb would be appropriate.

I really don’t want this injury there right in the middle of my lathe which has so far only served to remind me of my carelessness. It should be a constructive reminder, but the ego can be a fragile thing sometimes.

My main reason for posting this is maybe somebody will read it and not do the same thing.


----------



## erikmannie (Mar 3, 2021)

I plan to use the lathe another 30+ years. I would feel VERY stupid if I replaced it & then damaged the new one. At some point, somebody really just can’t have nice things.

Another choice would be remove, gas weld repair, and reinstall. It seems like this could be done in only a few hours. My CF is oil-based so the material has oil in it.


----------



## frankly2 (Mar 3, 2021)

Leave it there, it’s a good reminder to be cautious in the future ! I have many reminders in my shop ! It’s all in what we call a learning curve.


----------



## Weldingrod1 (Mar 3, 2021)

Dont weld or braze it! The chances of warping it are just too high! If you want to fill it, just use JB Weld and dress it flush after it sets.
I'd say -most- lathes have a few battle scars! A very common one is a torn out part on the T slot..

Sent from my SM-G892A using Tapatalk


----------



## Dabbler (Mar 3, 2021)

It really is cosmetic and the irritation it causes you over the next 40 years will serve as a extra incentive to be careful.  I put a scratch on my first mill that reminded me similarly to be careful!


----------



## rjs44032 (Mar 3, 2021)

OMG. It's trash now. Please ship the lathe to me. I'll scrap it for you. 

I guess I won't be displaying the scars on my lathe anytime soon. But after over 75 years, they haven't harmed the function yet. I would not worry about that except to knock down burrs so it doesn't catch the skin and to learn from. Hope this helps.

Best Regards,
Bob


----------



## projectnut (Mar 3, 2021)

It's one of those mistakes you learn from.  Back several years ago I was making a back plate for a new chuck.  At the time my only lathe had change gears.  I read the chart, selected the gears, and set everything up for cutting 1 7/16-12 threads.  Everything went according to plan, and after several cuts I made a final finish pass.  The threads looked like they were straight out of the factory.  I was so proud of my self my right arm grew 6 inches just from patting myself on the back.   I took the back plate out of the chuck, removed the chuck and attempted to screw on the new back plate.  As hard as I tried I couldn't make it fit.  

I measured the thread angle and depth until I was blue in the face, but still couldn't find the problem.  As a last resort I got out the thread gauges and stuck the 12 tpi one into the threads.  Close but no cigar.  I measured in several different places with the same results.  I went through a number of pitches and finally found the one that fit. It was 11 1/2 tpi.  I had inadvertently grabbed a wrong gear and spent an afternoon making a worthless part.  To this day I keep the part in prominent view so I can remind myself to double check everything before making a cut.

At the time I had never heard of an 11 1/2 tpi thread and had no idea what it would fit.  Just last year I needed to make an adaptor from a garden hose to pipe thread.  Guess what, a garden hose fitting is 11 1/2 tpi.  You live and learn.  Fortunately you made a mistake that only caused a cosmetic blemish.  It may have been the first, and hopefully it will be the last.


----------



## higgite (Mar 3, 2021)

Forget the ding! What are those ghastly scratches I see next to the tool post?  With a distraction like that staring you in the face, it’s no wonder that you inadvertently ran the compound into the workpiece.
<sarcasm off>  

As for the ding itself, smooth it out as best you can and if anyone asks, tell them it was needed for extra clearance on a special one-off project. Now get back to making chips. 

Tom


----------



## Buffalo21 (Mar 3, 2021)

That should buff right out!!.....................


----------



## Larry$ (Mar 3, 2021)

All good replies, except the welding one. I hate to say it, but it will get more dings with time. Just the nature of tools. Powerfeeds have a way of doing such things. Keep a hand on the control and feed the last little way by hand. Use the $ you considered spending on a shinny new part for more tooling.


----------



## Aukai (Mar 3, 2021)

I was so upset when I gouged my mill table I bought a brand new table for 600.00. It has been leaning on the wall for 5 years, I never put it on. ZH!t's gonna happen.


----------



## mikey (Mar 3, 2021)

Sorry to hear about this, Erik. 

You went into debt to buy your dream machines and now you've gone and damaged it, all because of your own stupidity, right? It's like parking your brand new car in the farthest corner of the lot to make sure some bozo doesn't park next to you and ding your door, only to open your door into a steel post you didn't notice. Been there, done that.

I get it, trust me, I get it. As you can see, most of us get it. I'm sure you've heard of the Arc of Shame and this is exactly what that is, or at least part of an Arc. In this hobby, there are those who have an Arc and those who will have an Arc; that's just how it is. I have an Arc on the face of the cross slide of my Sherline lathe. I got too close while trying to face off that last thou, even knowing the chuck was close to the cross slide. I got that last thou but after over 25 years on that lathe, I also got an Arc. You go through that period of self-flagellation but you eventually get over it and learn to be more careful in the future. 

My suggestion is to let it go for now. Don't go ordering parts. Instead, go make more stuff on your still beautiful lathe and give this some time. Eventually, the lathe will have scratches and dings here and there and that little ding won't seem like such a big deal anymore. The lesson will stay with you for the rest of your life and that will make you a better machinist.


----------



## macardoso (Mar 3, 2021)

erikmannie said:


> I bought this PM-1660TL new 4 months ago.
> 
> This was obviously 100% my fault. I had the compound set at 37 1/2°. My plan was to turn, groove & then cut the taper.
> 
> ...


Ooops, sh*t happens.

Good thing lathe still works fine, better that you aren't injured either. 

I'd TIG in a bit of bronze and file flush if you're really worried about the cosmetics.


----------



## SLK001 (Mar 3, 2021)

The first scratches come hard!


----------



## benmychree (Mar 3, 2021)

I agree, just deburr it, and don't fret over it; nearly every other lathe that you will ever see will have the same battle scars.  Any person that will say that they never had such a thing happen to them Are very likely not being completely honest.  If you want to go the JB weld route, I'd suggest drilling and tapping a hole in it and inserting a small screw to anchor the JB. I definitely would not weld/braze on it.


----------



## sdelivery (Mar 3, 2021)

I cant see any mark....where did you hit it?


----------



## silence dogood (Mar 3, 2021)

Once there was a farmer who had two apple trees next to his farmhouse,  One tree was beautiful, shapely, and put out bright green leaves to grace it's shape year after year, but no fruit.  The other was somewhat scrawny and the limbs were broken from the weight of an abundant of wonderful tasty apples for canning, cider, and for just plain eating.  After a few years, one tree got chopped down to make room for another building.  Guess which one?


----------



## Manual Mac (Mar 3, 2021)

My lathe spent many years in a high school with pimply faced kids learning on it.
Think about that.


----------



## FanMan (Mar 3, 2021)

Bought my lathe and my mill pre-owned and pre-dinged, at no extra charge.


----------



## graham-xrf (Mar 3, 2021)

erikmannie said:


> I plan to use the lathe another 30+ years. I would feel VERY stupid if I replaced it & then damaged the new one. At some point, somebody really just can’t have nice things.
> 
> Another choice would be remove, gas weld repair, and reinstall. It seems like this could be done in only a few hours. My CF is oil-based so the material has oil in it.


Erik - I am supposed to be the one having serious adventures welding on a compound!
That said, the PM version is probably made of weld-able steel - so the plan may be OK, but the ding does not affect function. You have no reason to want it out of sight other than you like the "new unblemished look". I think the folk here are trying to get you to appreciate it more, and show it some love. I admit that engraving the date next to it may be taking the fashion statement a tad too far!


----------



## SLK001 (Mar 3, 2021)

silence dogood said:


> Once there was a farmer who had two apple trees next to his farmhouse,  One tree was beautiful, shapely, and put out bright green leaves to grace it's shape year after year, but no fruit.  The other was somewhat scrawny and the limbs were broken from the weight of an abundant of wonderful tasty apples for canning, cider, and for just plain eating.  After a few years, one tree got chopped down to make room for another building.  Guess which one?



Okay, the suspense is killing me... Which one got cut down?


----------



## erikmannie (Mar 3, 2021)

I used some round files to start to even it out while I was waiting on a power feed. I can fine tune it when I can give it my full concentration.

I actually do put my finger there when I rotate the compound so I actually use this finger groove. Maybe I will start a service putting finger grooves in top slides. Who wants to be my first customer?


----------



## erikmannie (Mar 3, 2021)

SLK001 said:


> Okay, the suspense is killing me... Which one got cut down?



They cut down the unproductive tree!


----------



## silence dogood (Mar 3, 2021)

SLK001 said:


> Okay, the suspense is killing me... Which one got cut down?


Don't you like apple pie?


----------



## DASHINCHAMPION (Mar 4, 2021)

I remember a feature I used to have machined in the front of a set of jaws for my bosses at the time lathe. The feature was a simple recess that I used to grab very thin cylindrical parts. Well that's what everyone else saw. I always saw a big kick up the butt reminding me to always verify my power feed settings before engaging it while working close to the chuck 

Sent from my SM-A705YN using Tapatalk


----------



## martik777 (Mar 4, 2021)

Fill with epoxy and silver pigment?  
Make a thin plate under the QCTP extended out to cover the crater.


----------



## dbb-the-bruce (Mar 4, 2021)

Welcome to the club! there is a saying that goes something like - "There are only two kinds of machinists, those that have nicked a machine or fixture and those that are lying" 

No blood, cosmetic damage - It's a right of passage. You won't make the same mistake again. Clean it up so it's not sharp (as you already have) and move on.

I bought a brand new small precision vice a month or two ago and nicked it first time out 'cause the work piece was in another vice and that was what I was watching.


----------



## ArmyDoc (Mar 4, 2021)

SLK001 said:


> Okay, the suspense is killing me... Which one got cut down?


They cut down the productive one because, them city slickers only care about what looks good when they build their new housing developments after paving over productive farm land...


----------



## danallen (Mar 4, 2021)

I would leave it as a reminder to not do it again.


----------



## SLK001 (Mar 4, 2021)

silence dogood said:


> Don't you like apple pie?



I do, but you'd be surprised at the number of people today who would say, "Let's keep the pretty tree..."!


----------



## Tozguy (Mar 4, 2021)

Something like that happened to me.


But I don't think that any cracks will develop, all the stress was relieved into my shorts when it happened.


----------



## macardoso (Mar 4, 2021)

Tozguy said:


> Something like that happened to me.
> View attachment 357944
> 
> But I don't think that any cracks will develop, all the stress was relieved into my shorts when it happened.



I too have an identical mark - my fault. No harm done


----------



## erikmannie (Mar 4, 2021)

dbb-the-bruce said:


> ...I bought a brand new small precision vice a month or two ago and nicked it first time out 'cause the work piece was in another vice and that was what I was watching.



+1 for not nicking the work piece!


----------



## erikmannie (Mar 4, 2021)

Replacing the compound with a plinth would get rid of the scar, but I use my compound very often. However, only hours ago I was doing something that clearly required a plinth, and a custom shaped plinth at that.

The machine costs $15,999. The replacement compound assembly is readily available & in stock at Precision Matthews for $500. They only sell the complete compound assembly because it is hand fit. I’m going with the finger groove for now. John at Precision Matthews told me that PM intends to always have at least one of every replacement part for every machine they sell on hand IN Pennsylvania at all times! Precision Matthews continues to be amazing.


----------



## Gaffer (Mar 4, 2021)

I agree with your choice of a finger groove. I feel your pain with the damage, but fortunately, it's not that big of a deal in the scheme of things. The first one, and hopefully the last, hurts the most.


----------



## erikmannie (Mar 4, 2021)

In the photo below, you can see what I was doing that did not work so well with a compound. I was trying to put a groove in the welded, beveled joint. That 10.75” OD pipe extends below the cross slide (something that I will have to watch out for so that I don’t cut into my cross slide!).

Since I could get the cross slide only so close to the work, I had to extend the compound. Upon attempting to cut the groove, the extended compound vibrated even though the compound & carriage were locked.

If you’re thinking that a LH boring bar would work, think again because the cross slide cannot be pulled back far enough to use a boring bar. Plus, who puts a grooving tool on the end of a boring bar?




EDIT: after I posted this, I realized that I could pull the cross slide back all the way AND move the T-nut back in order to make room for a boring bar.

In any case, I don’t own a LH boring bar. It would appear that when the workpiece extends below the cross slide, you can only work on the first few inches of the workpiece. I would also like to have been able to part that 4” in.


----------



## macardoso (Mar 4, 2021)

erikmannie said:


> In the photo below, you can see what I was doing that did not work so well with a compound. I was trying to put a groove in the welded, beveled joint. That 10.75” OD pipe extends below the cross slide (something that I will have to watch out for so that I don’t cut into my cross slide!).
> 
> Since I could get the cross slide only so close to the work, I had to extend the compound. Upon attempting to cut the groove, the extended compound vibrated even though the compound & carriage were locked.
> 
> ...


Looks like you just justified a bigger lathe


----------



## erikmannie (Mar 4, 2021)

macardoso said:


> Looks like you just justified a bigger lathe



That’s what I’m sayin’ LOL.


----------



## silence dogood (Mar 4, 2021)

I think that this is a good lesson for all of us.  I believe it's "This old Tony" that he would check the carriage and turn the chuck by hand to make sure that there would be no crash.  Put a stop in and make sure it's screwed in tight.    At the same time, make sure that there is nothing loose or dangling.  Also make sure that you know where your hands are, before you turn it on.  I'd feel the same way as you, Would say some dirty words and berate my own stupidity. But continue on, no real damage was done.


----------



## erikmannie (Mar 4, 2021)

silence dogood said:


> I think that this is a good lesson for all of us.  I believe it's "This old Tony" that he would check the carriage and turn the chuck by hand to make sure that there would be no crash.  Put a stop in and make sure it's screwed in tight.    At the same time, make sure that there is nothing loose or dangling.  Also make sure that you know where your hands are, before you turn it on.  I'd feel the same way as you, Would say some dirty words and berate my own stupidity. But continue on, no real damage was done.



It is definitely a good use of time to spin the chuck in neutral and think through what will happen. There are a lot of places where a collision can occur.

I noticed the other day that if you start your machine with the cutting tool at zero, a slightly higher point on the workpiece can rotate around to the cutting tool before the chuck is up to speed. Best to allow a completely unobstructed path for the chuck to get up to speed before the cutting begins. This should go without saying, but I did it.


----------



## rabler (Mar 4, 2021)

macardoso said:


> Looks like you just justified a bigger lathe



The trick is not justifying a bigger lathe.  The trick is justifying why you're keeping this one AND buying a bigger one


----------

