Machinist Jack

[PJs]

This machinist jack was a quick gift for my brother. Not as pretty or versatile as others, like Pauls beautiful set but more about seeing if and how well I could turn 4140 on the peanut (mini). I've had a piece of 1" I got for another project which was kind of burning a hole in my pocket to give it a try, so off I went. I was also inspired by Brians ring gauge and the discussion of chatter and turning tools.

Years ago I had a Starrett "Little Giant" jack set and liked the versatility of it so I wanted to model the bases for it similarly for my brother. I haven't made the other parts for it but they can come later and the screw is a bit rudimentary, mainly because I didn't have any hex stock the right size to make one.

The first thing I had to do was cut off a piece of the bar so it would fit in the mini and would like to give a shout out for the Diablo Steel Demon blade I picked up a while back for the saws all!! Excellent finish results and felt like cutting aluminum!

Most of this I did on the fly and the pictures are mainly of the finished pieces but it's pretty self explanatory. I did mic it all at the end and put it in my sketch book to make a drawing from it and the future attachments.



Starting with a piece about 3.5" long, I used my bump roller to get it as true as I could then faced it off both ends and took a couple of clean up passes on the OD with a HSS bit. The top piece is tapered at 36º inclusive...not sure why, just was aesthetically pleasing. I used carbide TCMT inserts for hogging off most of it then switched to HSS for the final couple of passes. As you can see I got a bit of chatter in the middle section but think it was due to slop in the compound. All that was necessary was to use a 240 grit sponge and about 30 seconds with some crocus cloth to get what you see here.

Next was to drill (Q bit) and tap the hole for 3/8-24. Started with a center drill, went to a 1/4" and drilled as deep as I could, then to a 5/16" bit and finally the Q bit. Started the tap in the lathe maybe 6 threads. The mic'd the length of top and base plus enough for the counter bore and shoulder. Held it with a live center in the tail stock and proceeded to part it off by creating a groove where the shoulder would be on the bottom piece (shoulder diameter). Then moved the carrage over about a 1/16" (width of parting tool) and finished parting it off.

Once parted I reversed the top and faced it off to begin the counter bore. The mistake was using a carbide tipped boring tool. I should have taken the time to grind a HSS one because as I was getting into the last pass or two, it Hogged in on me. Ended up having to take it out a little further than I wanted to match the diameter of the bottom shoulder. It ended up with .015 radial clearance instead of .002-3 I wanted. Still works but not my best from being in a hurry. You can also see more chatter internally from the carbide.

Finished tapping the hole on the bench, then re-bored the bottom piece to a "W" bit for close tolerance through hole on the 3/8 screw. The screw was the only hex I had (3/8-24 x 1.5) so I faced the head and underside with an undercut at the top of the threads so I could be flush with the top with or without the nut. The nut was from 1/2" hex brass and made it .236 thick.

All Done I decided to blue it with some Birchwood Casey blue. A bit blotchy on the bottom piece but shouldn't rust. These are the finished shots.



Basically it can range from just over 1.6" up to about 3.8" safely.

[Christophe Mineau]

Hi PJ,
Really good looking little tool.
But can you explain some example of use, I am not familiar with them ?
Thanks !
Christophe

[PJs]

Thanks Christophe. They are mostly used for setups on a mill to support odd shaped or long pieces sticking out of the vice, and used with clamps once the part is level/square to the table and spindle. I used 3/8"-24 to get a lot of fine adjustment (~.01 per 1/4 turn) and is slightly stronger than course thread. Most commercial ones will provide 1000lbs support of clamping pressure so the setup is very rigid for milling. They can be used on a Drill Press as well for the same purpose.

It is also possible to use them to support shallow angles, rods, channels, etc., with different head designs and also horizontally. Could even be used as an internal press if need be to press something apart, I think. Not sure what the 4140, grade 5 bolt and threads will take on mine but would guess it could take 1000lbs (450Kg).

Thanks for asking the pertinent question! ~PJ

[Christophe Mineau]

Thanks for the explanation ! very clear.

[Paul Jones]

PJs,

Excellent finish on the 4140 proving the "peanut" (your mini lathe) produces exacting work. Cutting a taper with a fine and even finish with the compound on a mini is a challenge. This will be a wonderful gift for your brother, the machinist. Thank you for several tips in your narrative. I am looking into the 14/18 TPI metal reciprocating saw blades by Freud. I use several versions of the Freud table saw blades for cabinetmaking and have been pleased with their products. Also, the use of Birchwood Casey blue for the final finish is another good tip.

Thanks for the compliment about the small machinist jacks and accessories posted some time ago. These are now used mainly as spacers for cutting odd-shaped parts on the horizontal band saw. I don't think we can have too many clamps and machinist jacks in the shop.

Thank you for posting your work and taking us through the processes you used. There is a lot of good information.

Regards, Paul

[PJs]

Excellent finish on the 4140 proving the "peanut" (your mini lathe) produces exacting work. Cutting a taper with a fine and even finish with the compound on a mini is a challenge. This will be a wonderful gift for your brother, the machinist. Thank you for several tips in your narrative.

Thank you Paul. I was a bit surprise to only use 240G and crocus to finish it off. I thought it was going to be like the G2 grey bar I used on my taping guide, but it was actually kind of nice to work. I did think of using the shear bit as we discussed in Brian's post but felt it was good enough for the use it will get. Actually my brother isn't a machinist by trade but does have a Grizzly G0760 Mill/Drill and a 1943 SB13 x 6' he picked up a while back. He is getting there though and will soon have more time to do it!

I'll be looking for the Freud blades for my little Ryobi miter saw and my old Porter Cable cabinet circular saw. Really impressive blades IMHO.

Agreed, never too many clamps. What I thought was ingenious about your machinist jack build was the ball bearing...Very cool! Interesting use and a good topic possibly for various uses of these versatile & handy little tools.

Thanks always for your kind feedback and great contributions to the forum!! ~PJ

[C-Bag]

Great job all the way around Wiz. I'm sure your bro is going to be happy to receive such a nice piece made by your own hand.

And really good tip on the recip blade. I'll have to get some. I was disappointed that they don't make a blade like that for the band saw I'm always on the lookout for metal cutting blades for my horizontal metal cutting bandsaw and my converted from wood to metal cutting 14" vertical bandsaw. Because the 14" is typically used for wood it's tough to find good metal blades for it.

[Paul Jones]

PJs,

Please do take this as an advertisement for Freud but I like their products. In the case of your table saw, I highly recommend buying the Freud LU87R009 9-Inch 22 Tooth ATB Thin Kerf Ripping Saw Blade for your general purpose blade. For most work, you don't need a larger blade. The blade is designed for ripping and does so without any hint of circular tooth marring or blade burn marks. The really nice thing about this blade is it does this just as well with cross cutting so it is rare when I change the blade to a true cross cutting blade. The Freud PermaShield Coating makes the blades silky smooth. I use one of their 80 tooth cross cut blades on my 10" compound miter saw and the cuts are glass smooth (I can easily cut off 0.01" at a time using the side tooth clearance as a gage to sneak up on a perfect fit). I work mainly with oak, mahogany, teak and birch where these blades cut very well.

Paul

[PJs]

Great job all the way around Wiz. I'm sure your bro is going to be happy to receive such a nice piece made by your own hand.

Thanks C-Bag, he did really like it. What's a brother for¿ The Saws All blade blew me away actually...maybe 20 seconds to cut the 1" 4140. What brand is your 14" bandsaw? Did you put a VFD on it or change the pulleys? Been eyeballing around for one and could get Dads old Craftsman...just didn't think it would do much other than thin aluminum and wood.

Please do take this as an advertisement for Freud but I like their products. In the case of your table saw, I highly recommend buying the Freud LU87R009 9-Inch 22 Tooth ATB Thin Kerf Ripping Saw Blade for your general purpose blade. For most work, you don't need a larger blade. The blade is designed for ripping and does so without any hint of circular tooth marring or blade burn marks. The really nice thing about this blade is it does this just as well with cross cutting so it is rare when I change the blade to a true cross cutting blade. The Freud PermaShield Coating makes the blades silky smooth. I use one of their 80 tooth cross cut blades on my 10" compound miter saw and the cuts are glass smooth (I can easily cut of 0.01" at a time using the side tooth clearance as a gage to sneak up on a perfect fit). I work mainly with oak, mahogany, teak and birch where these blades cut very well.

Paul

Thanks for the recommendation on my saws. Don't actually have a table saw but a little 8-1/4" Ryobi compound miter saw that came with a "Six Pack" set I picked up at a yard sale "cheap" in Great shape and an Old Porter cable 7-1/4" circular saw with a large cabinet makers plate. Both do the job but pretty messy cuts. That 22 tooth sounds perfect for general use and might be nice for the circular too if available in 7-1/4". I've had terrible luck with plywood blades on the circular saw.

I like the idea of that 80 tooth cross cut...will check them out for my compound miter. My son got one of the Dewalt contractor 10" table saws a while back I was real impressed with their blades too, smooth as glass and no fray out on the back side. But alas I'm a total novice with wood working and will gladly take your advice, plus what I experienced and read about with the Freud they are about the best I think. Thanks Much!

~PJ

[C-Bag]

Thanks C-Bag, he did really like it. What's a brother for¿ The Saws All blade blew me away actually...maybe 20 seconds to cut the 1" 4140. What brand is your 14" bandsaw? Did you put a VFD on it or change the pulleys? Been eyeballing around for one and could get Dads old Craftsman...just didn't think it would do much other than thin aluminum and wood.~PJ

I just always used my HFT horizontal in the upright/vertical mode for stuff and it was ok but very dangerous. Then I saw on some other forum that guys were asking about converting those 14" vert bandsaws that HFT makes a direct knock off of the old Delta/Rockwell all cast iron saw for metal. After the chorus of "Chinese junk" the discussion got down to blade speed fpm and several came up with around 110 fpm to 190 IIRC. Stock for wood is 3,000 fpm. Then looked at YouTube and got a couple of ideas. No VFD, made a jackshaft double reduction. Even at slow speed with the wood blade it cuts fast and I do almost no woodworking.

If you want, I've been thinking about posting my humble mod of my HFT 14" to cut metal. I watched for a long time and picked up one locally for $75. The most expensive part of the mod was buying the nice blade guides online somewhere because I didn't have all the tooling and know how to make them at the time. It's been a great thing and is waaaay safer to use than the old horizontal bandsaw in vertical mode.