Machinist Jacks

Toolmaker51 said:
I will hardly address single participants in a forum, we all sit at a really big table.
Some commenters feel 'late' input is a lower tier of involvement. Not so. Check the home page, there are how many posts - not merely original threads? Discount likelihood your interests expand, to the point interest and searches take you into different territory. Barring some calamity, this information isn't volatile, 'newbies' are born everyday, methods expand because someone experiments, even when some of those fail.

Point is, machinist jacks are invaluable. Depending on workpiece size, many unaware just how large those get, capacity in 1000's of pounds.

- Personally, use of jacks is more of an inspection necessity, on a surface plate; leveling a casting or compound angular features to pull measurements. Sorry to point out, that means 3 jacks are a set.
- 2 suffice but require a 3rd element (even if not adjustable) somewhat higher than minimum the adjustable pair can do. Note; few commercial sets offer that option, seeing only potential as setup components.
- Adaptable (different heads, feet & bodies) jacks should be the standard. That makes logical argument for a case containing all the bits, easily transported to work area. Have a minimalist trait? Use an empty soup can.
- Any that cannot be set lower than your vise bed are worth avoiding. Of variety being castings, they will lose thread depth (and load bearing capacity) if you consider shortening them. Cutting foot bottoms out the screw.
- Very few (commercial) have good proportions of decent thread diameter, and fine thread pitch. Shop made versions never seem to follow that mistaken intuition. Try leveling a 20" long workpiece .002 with 16 TPI - 1 revolution @ 0.0625th inch - 0.002 is a serious feat of dexterity (0.0003472 increments of a turn).
- Well done, close fitting threads deserve complement. But without holes for tommy bar or wrench flats, very hard to turn under moderate loading.
- The concentric ring pattern is more practical than cosmetic. Unlike gauge blocks, rarely a workpiece and jack are equally clean, those are recesses for dirt, and irregularities on castings. The user, while scooting jack, around detects stability.
- Sometimes that enlarged surface shifts part laterally as it turns; if pointed, averts that. Alternately, make cap independent of screw.
Click to expand...
Thank you very much for posting and for all the useful information!
 
@firemaker76 Those jacks look really awesome, I would be extremely proud of myself if I could make anything close to that. I'm just getting started again with a lathe, used one a long time ago in High School metal shop.
I signed up for a Hobby-Machinist mentor and I've been watching ThisOldTony, Mr Pete, & Blondihacks and others in preparation since I'm inching closer to retirement. I've been spending too much money on getting the garage all setup for that.... I don't have a mill though (yet, maybe wait till I get more comfortable on the lathe).

Are those jacks something I should try to make, or maybe start with a more "beginner" friendly project? Do you have any drawings or web links I could learn more about the steps?

Thank you for sharing.
Phil
 
Weren't the old south bend high school so projects inclusive of machinists jack's? I think it would be good, but you will need to get threading first.

Sent from my SM-G970U using Tapatalk
 
Thank you @silverhawk, I'll practice first with facing, turning, threading, and parting pieces to get a feel for the machine. Its nice to have a goal or project to focus on, to start down the path. Your memory is better than mine, I know only the lathe was big and I do remember doing some turning but don't remember what I made.
 
PhilJustLearning said:
@firemaker76 Those jacks look really awesome, I would be extremely proud of myself if I could make anything close to that. I'm just getting started again with a lathe, used one a long time ago in High School metal shop.
I signed up for a Hobby-Machinist mentor and I've been watching ThisOldTony, Mr Pete, & Blondihacks and others in preparation since I'm inching closer to retirement. I've been spending too much money on getting the garage all setup for that.... I don't have a mill though (yet, maybe wait till I get more comfortable on the lathe).

Are those jacks something I should try to make, or maybe start with a more "beginner" friendly project? Do you have any drawings or web links I could learn more about the steps?

Thank you for sharing.
Phil
Click to expand...
Thank you for your kind words Phil,
These jacks were actually an idea from another youtuber that I made a couple slight alterations to. I will try to find the link and send to you. Machining 4140 is somewhat more involved than say aluminum or brass so you may want to just practice on turning a piece for practice before jumping into the actual project. I can tell you, you don't want to try to take light cuts or run a slow feed....your surface finish will look terrible. In my experience, the trick to machining heat treated 4140, is to take a fairly agressive depth of cut and use a moderate feed rate.
The only way to take heavy cuts and end up at your desired diameter (within .001" or so), is to calibrate your DRO (if your lathe has one) as you're turning your part. The rule of thumb is to make sure that at least your final two depth of cuts are the same.
Basically you would take a cut across the length of your part. Then, WITHOUT moving your cross slide (or WITHOUT changing your X axis), mic the diameter of your part and enter that value into your DRO. Now, you take another cut; WITHOUT moving your cross slide, mic your part; and compare the reading to your DRO. If your DRO reads the same as your mic, then you are calibrated for that DOC. If your DRO doesn't match the mic reading, then enter the mic reading into your DRO again and repeat. Changing your depth of cut will change the load against your cutter so for this to work, at least your last two cuts have to be the same DOC. This process works extremely well to get you within specs of your final diameter when taking heavy cuts. That is the reason that most people try to sneak up on a final diameter, but that won't work with 4140. Trust me, it seems counter-intuitive at first because it's hard to believe you can get so close to final diameter when taking heavy cuts, but if you calibrate your DRO, it will work exactly as I've described above. Trust the numbers and you will get good results. Hope this helps.
 
PhilJustLearning said:
@firemaker76 Those jacks look really awesome, I would be extremely proud of myself if I could make anything close to that. I'm just getting started again with a lathe, used one a long time ago in High School metal shop.
I signed up for a Hobby-Machinist mentor and I've been watching ThisOldTony, Mr Pete, & Blondihacks and others in preparation since I'm inching closer to retirement. I've been spending too much money on getting the garage all setup for that.... I don't have a mill though (yet, maybe wait till I get more comfortable on the lathe).

Are those jacks something I should try to make, or maybe start with a more "beginner" friendly project? Do you have any drawings or web links I could learn more about the steps?

Thank you for sharing.
Phil
Click to expand...
Hi again Phil,
Here is a link to one of the videos on these machinist's jacks. This was a colaboration between two individuals, so there are several other videos that show a lot of detail and can probably answer a lot of your questions.


-Mitch
 
firemaker76 said:
Thank you for your kind words Phil,
These jacks were actually an idea from another youtuber that I made a couple slight alterations to. I will try to find the link and send to you. Machining 4140 is somewhat more involved than say aluminum or brass so you may want to just practice on turning a piece for practice before jumping into the actual project. I can tell you, you don't want to try to take light cuts or run a slow feed....your surface finish will look terrible. In my experience, the trick to machining heat treated 4140, is to take a fairly agressive depth of cut and use a moderate feed rate.
The only way to take heavy cuts and end up at your desired diameter (within .001" or so), is to calibrate your DRO (if your lathe has one) as you're turning your part. The rule of thumb is to make sure that at least your final two depth of cuts are the same.
Basically you would take a cut across the length of your part. Then, WITHOUT moving your cross slide (or WITHOUT changing your X axis), mic the diameter of your part and enter that value into your DRO. Now, you take another cut; WITHOUT moving your cross slide, mic your part; and compare the reading to your DRO. If your DRO reads the same as your mic, then you are calibrated for that DOC. If your DRO doesn't match the mic reading, then enter the mic reading into your DRO again and repeat. Changing your depth of cut will change the load against your cutter so for this to work, at least your last two cuts have to be the same DOC. This process works extremely well to get you within specs of your final diameter when taking heavy cuts. That is the reason that most people try to sneak up on a final diameter, but that won't work with 4140. Trust me, it seems counter-intuitive at first because it's hard to believe you can get so close to final diameter when taking heavy cuts, but if you calibrate your DRO, it will work exactly as I've described above. Trust the numbers and you will get good results. Hope this helps.
Click to expand...
Thank you @firemaker76 for explaining the details for the 4140 steel material approach, I'll look into those bits and pieces... Your right, it does sound counter-intuitive.

I know you need to be careful with abrasives around your lathe, after protecting the bed and other key surfaces would it be possible to do the final rounds of surfacing with an aluminum oxide abrasive? Just thinking out loud. Maybe that is a bad idea, I don't know enough at this point. I haven't seen anything where folks are using abrasives on their lathe in this way to reach the final tolerances and get a nice surface too. Although I do know abrasives are used in high precision surface grinders.

Since I have a Sherline 4410 CNC (I ordered a PM-1340GT and that baby is scheduled for delivery in Aug/Sept, with a DRO of course :) ), I was thinking to practice first with 6061 Al manually unless you have a suggestion for a better/different material to use. Not sure if the 4410 lathe would take well to the 4140 material. I looked up 4140 on Wiki, they mention chromoly which is a term I heard before on the Extreme-4X4 and other car shows I watched and they use it for roll-cages among other things. I would imagine the 4140 is tough enough out of the box and is why machinists use it to make this kind of tooling. I wonder if there are other steel options that may be easier to machine and get a nice surface, then do a casehardening process to it at the end, like carburization. (I do intend to learn to process 4140 steel, when the time is right & I do think it would be a good skill to acquire.)

Recently I looked into the Al anodizing process and was absolutely amazed that it makes aluminum oxide on the outer surface of aluminum and increases the hardness to 60-65 Rockwell C (this happened because I was looking into Air Bearings for a project, which would be cool to make!, and I found this video
).
So the idea would be to machine 6061, get it hard coat anodized (optionally with some color), then use this for tooling. There may be some downsides to this. Where I live there is a company that does the anodizing, I don't know if it is expensive. Also, using steel may just be stronger (stiffer) and won't yield as much as Al for milling operations, don't know.

Phil
 
firemaker76 said:
Hi again Phil,
Here is a link to one of the videos on these machinist's jacks. This was a colaboration between two individuals, so there are several other videos that show a lot of detail and can probably answer a lot of your questions.


-Mitch
Click to expand...
Hi @firemaker76 ,
Order of operations, that is exactly what I need! Watching now ... thank you.
Phil
 
PhilJustLearning said:
Thank you @firemaker76 for explaining the details for the 4140 steel material approach, I'll look into those bits and pieces... Your right, it does sound counter-intuitive.

I know you need to be careful with abrasives around your lathe, after protecting the bed and other key surfaces would it be possible to do the final rounds of surfacing with an aluminum oxide abrasive? Just thinking out loud. Maybe that is a bad idea, I don't know enough at this point. I haven't seen anything where folks are using abrasives on their lathe in this way to reach the final tolerances and get a nice surface too. Although I do know abrasives are used in high precision surface grinders.

Since I have a Sherline 4410 CNC (I ordered a PM-1340GT and that baby is scheduled for delivery in Aug/Sept, with a DRO of course :) ), I was thinking to practice first with 6061 Al manually unless you have a suggestion for a better/different material to use. Not sure if the 4410 lathe would take well to the 4140 material. I looked up 4140 on Wiki, they mention chromoly which is a term I heard before on the Extreme-4X4 and other car shows I watched and they use it for roll-cages among other things. I would imagine the 4140 is tough enough out of the box and is why machinists use it to make this kind of tooling. I wonder if there are other steel options that may be easier to machine and get a nice surface, then do a casehardening process to it at the end, like carburization. (I do intend to learn to process 4140 steel, when the time is right & I do think it would be a good skill to acquire.)

Recently I looked into the Al anodizing process and was absolutely amazed that it makes aluminum oxide on the outer surface of aluminum and increases the hardness to 60-65 Rockwell C (this happened because I was looking into Air Bearings for a project, which would be cool to make!, and I found this video
).
So the idea would be to machine 6061, get it hard coat anodized (optionally with some color), then use this for tooling. There may be some downsides to this. Where I live there is a company that does the anodizing, I don't know if it is expensive. Also, using steel may just be stronger (stiffer) and won't yield as much as Al for milling operations, don't know.

Phil
Click to expand...
Phil,
I think you'll find that once you've gotten the calibration technique down, you'll have very little need to use abrasives for attaining good surface finish. Now on stock that is smaller diameter (5/8" and smaller), that is a different story. You may have to use some 3M scotch brite or something similar to get a nice surface finish. Most manual lathes won't spin small stock fast enough to get that beautiful surface finish on 4140. I would also recommend using the heat treated 4140...that helps a lot. There are many individuals on here with much more knowledge and experience than me, so these are just recommendations based on my own experiences.

-Mitch
 
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