# Machinist jack (a small project with a long story)



## ShawnR (Apr 26, 2022)

I had an urge to do something on the lathe. Just make something. Anyone else get those moods? Decided to do a machinist jack. I think pretty much every Youtube machinist makes one in one of their episodes so they keep popping up in my surfing. I have never had one. Did not know what they were for. Since I have been working with the mill recently with the upgrades, I came across a Blondie video on basic mill tips, which showed clamping and working outside of the ends of jaws of the vise and I realized that I needed at least one jack. The recent thread, here, on clamping was a catalyst for those searches.

So I measured to the bottom of the vise (3" when on the rotary bottom), grabbed a chunk of mystery metal from my bench and loaded it up. I wanted to do my own thing rather than follow someone else's plans, but I used ideas/suggestions from those videos. The piece I grabbed is probably too short, or maybe borderline for the size I needed. I needed 3" to the bottom of the vise, but most things sit on parallels. And I would be adding the screw and top. The piece I had was about 3.5". So I figure more lessons will be learned. I posted previously on a thread that one always learns from doing, "anything", so my goal is to learn something, and not get hurt or break anything in the process.     A benefit of being low in the learning curve. 

First thing I did was overshoot my projected o.d. Good thing it was not important! First lesson learned, 5 minutes in! 

I played musical cutters (left, right, center?) for a while, trying to figure out how to cut in on the taper, but then consider the end, where I was getting too close to the chuck. Realized that it did not have to be one cutter to do it all. The carbide cutters were cutting off long strings of metal, regardless of my DOC. Not sure if that means it is good stuff or crappy, but with the finish I was getting, I think this material is something good. I had to stop progress to make a drill adapter to spin the compound in. Been wanting one of those anyways, a power feed on the compound.(2 projects in one!) I noted, that yes, my cuts were too light for a carbide bit, but turning the compound in yielded a poor finish, but when I backed it out, on the same settings, the finish cleaned up nice. Don't know why but it was working for me. As I type this, I realize I could have cut left to right. That might have been better. I went right to left, so just stopped each cut near the end, but not very precisely. Then, when the taper was done (close enough...forgiving project), I cleaned up the end near the chuck (top of the jack).

So. after cutting it as shown, no more photos right now, I realized that maybe I should have drilled and tapped the hole first? But then would the live center steady it enough for those taper cuts? Maybe I did not even need the center. I think it is 4x the diameter recommended max stickout? so technically, could have hung it out 5.5 " but the jaws were only gripping  about a half an inch, so I figured not enough to do it without a tail support. The od "just" fits into my bore so I was able to slide it back into the chuck and clamp on the bottom to drill the through hole, but it took a bit of adjustment to get it to run true because the jaws were not really grabbing very much, without resting on the grooves in the jaws. I did get it true enough that I could drill the hole. 

I have a piece of 1/2" fine all thread for the post and will take the cue from This old Tony in his version and weld and turn the cap for this one, versus making the post from one piece. I dished the bottom, taking a cue from Quinn. 

We seem to be getting several new members with new lathes so I figured I would post this as a good newbie project.  If anyone wants to chime in on the order of operations that you would have done with this project, I would like to hear it, cause I was guessing and flipping coins..... The taper combined with the short piece was a bit of a challenge, for me. When I look at projects, I often find myself trying to figure out the order of operations. It is interesting to see, with odd shaped final projects, what needs to be done first and how that affects the process.


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## ShawnR (Apr 26, 2022)

As mentioned in the last post, this is a mysterium metal from my scrap pile. But, would anyone know what kind of metal or qualities exhibit the light show I was getting on it? Also, the fine "hairs" sticking out of it?  I tried a bit of a scour pad and 180 sand paper but they seemed persistent.






I thought welding the top on while sitting in place was a good idea for alignment reasons but probably should have tacked it, then backed it out of the base. The base cleaned up nice though.

But other than those peculiarities, I am happy with it. Nice small turning project that will probably come in handy. I probably pictured a mirror like finish but realistically, the finish allows a good grip on it, cause, you know, that is important....


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## Brent H (Apr 26, 2022)

Great work @ShawnR  - nice project!   could be a higher chrome steel you have there?


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## ShawnR (Apr 26, 2022)

Brent H said:


> Great work @ShawnR  - nice project!   could be a higher chrome steel you have there?



Thanks @Brent H I have used this stuff before and it is the only metal that I have ever seen that gives me those sparks while turning. I keep thinking it is the rod from a hydraulic cylinder but don't know for sure. I probably just threw it in the trailer while "shopping" at one of our scrap metal dealers many many years ago. It machines nicer than the usual mild steel I work with.


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## RobinHood (Apr 27, 2022)

Nice project Shawn! Worked out well. And you now have a new tool in the shop.

As far as the light show: could be a combination of factors.

The material - I think it is higher chrome steel - certainly not mild steel. So the material is probably around 30-35 Rockwell C and the carbide insert may not be the best suited for this type of material. There are special grades of carbide for harder materials.

The speed and DoC (looks like you were not really cutting but more ”rubbing”). You got quite a bit of tool deflection as witnessed by the spark show continuing on the carriage reversal. Could also just be the geometry of the insert and not deep enough DoC. The tool needs “to bite” into the material behind the top radius. If it is only lightly engaged (shallow DoC), then the chip formed may not be wide enough to be behind the top radius thus deflecting the insert away from the work. Same phenomenon can be observed at the nose radius of an insert. That is corrected by increasing the feed rate (assuming DoC is adequate to begin with).

The “fine hairs“ are another indication that the chips were not being formed properly because (most likely) the insert was “not working hard enough”. Most carbide inserts do not like shallow DoC like you can take with HSS. Unless you get very specific ones ($$). Typically the ones well suited for SS work reasonably well with shallower cuts in steel.

Some people have found flood coolant can make a difference when cutting harder steels.

If you have some more of that material and don’t mind experimenting a bit, try slower speed and a deeper cut but higher feed rate. Your lathe may “groan” a bit as it now has to work as well (not just the insert). When you get nice “C” or “6” shaped chips that change from light straw to (light) blue as they fall into the chip pan, you know that you are in the more “ideal” range of material removal. You may find that the light show stops and there is no/very little tool deflection after a pass.


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## ShawnR (Apr 27, 2022)

Thanks @RobinHood  That all makes sense. I think the material is the rod from a hydraulic cylinder. I expected those to be just chrome plated but it must be some kind of an alloy.  When I was making more aggressive cuts, earlier in the project, the pieces coming off were long strands. No chips per se. I tried different speeds and DoC in an attempt to get chips because they were kind of dangerous, as anyone here could imagine. But it seemed that it was just thinner or thicker strands that resulted.  I will see if I have more material to experiment with.  I used the top part, excess piece from that little jack to make the top so that whole piece got used up.


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## Susquatch (Apr 27, 2022)

ShawnR said:


> I had an urge to do something on the lathe. Just make something. Anyone else get those moods? Decided to do a machinist jack.



Yup. I get those moments too. I keep a list of potential jobs on a pad that is on the steel wall in my machining area. Most of the stuff on that list are repairs or mods, but a few are short nifty projects. When I get in a bit of a funk I pick something and do it. Even when I fail, I always feel better afterward. 

Did you see how @thestelster uses one of those machinery jacks in his bandsaw? I did the same thing. It is a great tip. Today, I used one on the vise on my mill too.


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## YYCHM (Apr 27, 2022)

Another use for a machinist jack
					

I had to move a sidewalk block about ¼”.  They’ve been in the ground for a while and a bar didn’t work.  This did.




					canadianhobbymetalworkers.com


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