New base for my lathe

S

skeetlee

Active member
I need a new base or foundation for my little Jet lathe, and i need one bad!! The piece of chit tin cabinet that comes with the lathe isnt worth a hoot, and if i spin my machine very fast the lathe will move. I have talked about this before, and now i think i have an idea as to what i need to do.
I have priced out steel a couple different times now, and it will cost me about 300 bucks to build a base like i think i need, if i build it out of steel. I have tried to locate some steel other than from retail dealers but i havent found what i needed as of yet. What i am thinking about doing now is to build the base out of concrete. Solid concrete, rebared to my floor. I can build the forms with my eyes closed, so that wont be an issue at all, and i even know how i will build them. I will use the original chip tray and modify the concrete stand to have a chip drop box easier to clean the chips out of. I will just cut a hole in the metal chip tray and sweep the chips down into the drop box.
Since i am a concrete man, i know all of the redymix companies in my area, and i know that i can get a discount on an over order. If a contractor orders 8 yards and only uses 7, the redymix will just dump the extra yard, or they will sell it to someone like me for less than half the normal price. I can build this stand for probably 50 bucks.
My big question is this. Will i have any issues with vibrations or funny harmonics with the lathe sitting on a solid block of concrete? I will also have to figure out a system to level the lathe once set down onto the concrete. Any thoughts on this? thanks Lee
 
Save your money Skeet. Save it to put on a bigger, heavier, lathe. The more of a silk purse you are trying to paint on it, it still is going to be a sows ear.

A bigger, heavier, base will help some of the problem you are having with vibrations at high speed, but it will not help with accuracy or rigidity that is caused by
Jet's design of that headstock. Even a 10,000# lathe will vibrate some at high speed if it is turning an off center load, just slow down some, the vibrations will abate.

As to using steel plate to form for the concrete, it will add very little over using a cheaper wooden form for the concrete.
 
Fellas i know what my lathe is, but i must say i have zero issues with my lathe not being accurate. Actually its quite accurate for what it is and if i can improve the unit for 50 bucks shouldnt i do that? I will one day soon have a better machine but even then i am not 100% sure i will give up this one. The belt drive on this little lathe of mine is very smooth and i can turn a tenon with zero run out front to back. I can dial barrels in to just under .0005 and my chamber run out is less than .0005. This machine works its just light. I like using my 4 jaw on new barrel, but the weight of the chuck with a barrel clamped in really induces some vibrations, and i know its because of the cheap ass cabinet. At least that has to be some of it. Im talking anything over 400rpm and i have movemnet. Thats not exceptable to me. I can built a base with WOOD forms and make a great base for 50 bucks. I just need to know if concrete will be ok, or if there is something i need to know about concrete and tooling operations. I assume there isnt going to be any issues, but i like to do some research. There has been a lot of really good winning barrels chambered on a lathe just like mine, and the barrels i am producing currently are shooting way above my expectations. I just need to control this movement.
I am always looking for a heavy 10. I look everyday in fact. The trouble is, i dont know what to look for and what not to look for. I am not a machinest my any means, and i might not know if a machine i was interested in is worth a hoot or if it needs a complete rebuild. I want the southbend heavy 10 that tom Haverkamp has. Man oh man is that one a cherry!!! Ill get one, but for now i need to do with what i have, and if i can improve this unit for 50 bucks, then thats what i need to do. Heck i can spend more than 50 bucks, just crossing the street. Its not like im talking about a lot of money, and i have the ability. thanks men, always appreciated. Lee
 
if you put on a new base, you will have to relevel the lathe.....now what is the water table like where you live?
i do not remember how thick your floor was .....

just thing to consider whe re-installing the lathe...what else will/can move.

its your time and money and i am in the same club, so go for it.
mike in co
(on the west coast there was a very precise large granite plate installed for inspection work on aircraft parts....something like 12' x 20'.
it was on the south end of san diego bay.....it was VERY heavy and the whole table moved when the tide went out.....so they had to post tide tables and ensure tide was in to use the very expensive table.)
 
Skeet...you might look into a better quality 4 jaw or Adjust-Tru 3 jaw chuck...I have found the cheep Chi-Com 4 jaw chucks are notorious for causing vibration due to poor balance...at shilen they use some light Jet and Enco lathes for chambering...and they have 1-1/4" rifle barrel blanks that are bolted to the lathe bases to widen the footprint which helps remove some of the vibration from being top heavy...In my opinion the concrete would work fine as long as the lathe was level and square...a better chuck and wider footprint would be a great improvement...look into the 3 jaw Adjust-Tru chucks they are a neat alternative to a 4 jaw for most gunsmithing type work...

Eddie in Texas
 
Skeet,

In re: your machine wandering around, my retired machinist father told me they used (back in the sixties) to bolt their lathes down via a redhead or something similar...I don't remember exactly. In effect, making the machine heavy. They would put a bolt or two on the stud, top it with a substantial washer, set the machine down on the studs, level it, and put a washer and bolt on top and tighten it down. Check level again and adjust...and adjust...or adjust them till' they cut straight.

I did this to my old Atlas with redheads. I remember it working out well.

There are variables, I'm sure. Slab thickness, machine weight, etc.

It was easy enough for me to do...I'm sure you could handle it.

Hope it helps,
Justin
 
The concrete bases were commen during WW2 with South Bend actually having a pamphlet on how to make them to ensure better accuracy. Try checking on one of the South bend Boards.
 
I bolted my South bend heavy 10 down and it did not like that at all. Went back to a nice set of leveling feet and it remains very accurate and happy.

John
 
The machine dealer I bought my lathe from told me about several lathes that had had the cabinet filled with concrete, said the mass improved the performance of all the lathes........just make sure it's in the right place before filling the cabinet, especially on some of the bigger lathes.

Lee since it won't cost much for the concrete fill the existing cabinet and see how it works, I wouldn't use rebar just concrete for mass and vibration dampening............Ian
 
Most machine shops cut a hole in the floor a little larger than the machine footprint, dig down and pour a footing to the machine manufacturers recommended depth, put expansion joint material between the machine pad and the original floor. Then if the machine still vibrates, relevel until the machine stays level, then work on the machine cabinet or machine proper. If you plan on a bigger or heavier machine in the future then make the pad larger and deeper now instead of redoing it then. Seen it done several times when I was still working at Cessna aircraft. Good luck. Max
 
Max Shaffer said:
Most machine shops cut a hole in the floor a little larger than the machine footprint, dig down and pour a footing to the machine manufacturers recommended depth, put expansion joint material between the machine pad and the original floor. Then if the machine still vibrates, relevel until the machine stays level, then work on the machine cabinet or machine proper. If you plan on a bigger or heavier machine in the future then make the pad larger and deeper now instead of redoing it then. Seen it done several times when I was still working at Cessna aircraft. Good luck. Max
Click to expand...

These are known as isolated bases. Their purpose is to isolate other shop vibrations from individual machines. For example on a 48 x 228 Monarch engine lathe we would pour about 25-30 yards of concrete for the base. The individual machines like this long bed lathe would actually "float" on this base. i.e. the machine would not be tightly fastened to this base, just sit on the jack screws. Reason, the isolated base actually crawls around the days heat and the nights cooling and concretes nature of moving as it cures,
 
Maybe ya' just need to do as my 1918 "Machinerys' Handbook" suggests,,,,,,,, make your shop floor out of 'hard' maple,,,,, end grain up! Seriously, I'd look into a different chuck. Those that come standard with the small imports leave a lot to be desired. A quality chuck, mounted on a back plate that has been 'trued' to the spindle will help a lot (it'll, also, enhance accuracy). Break down and buy a bit of steel, square or rectangular heavy walled tubing, and build legs with screw adjustments for leveling. How long does it take concret to fully cure?
 
Lee, before you spend $300-$800 on a new chuck, chuck up a piece of known balance like a 6" long piece of 1-1/2" or so round stock that is solid-no hole. Hold in the chuck by about 2" then carefully indicate the 4" sticking out of the chuck. Indicate at the chuck first then check at the end. Chuck with the bare jaws.

If you get a zero reading at the chuck and a zero reading (or near zero) at the end, then spin it to the rpm you are getting vibration. If you are still getting significant vibration then your chuck may be the problem. If you get a zero reading at the chuck then get significant runout at the end, say 0.005" or more, you have a warped chuck or poorly ground (or damaged) jaws.

Chuck and unchuck this piece 3-4 times and rerun the test to make sure you are not cocking the workpiece in the chuck.
 
lee, I bought a heavy (2000+lbs) JET 13x40 lathe in 2005, and was concerned with the vibration at 650rpm & above. Called the nearest JET dealer (170+miles away) and he was good enough to bring a mechanic out to have a look at the machine. After checking the deflection of the OEM 3-&4-jaw chucks on the lathe's D1-4 spindle, he declared that "These chucks aren't worth the powder it'd take to blow 'em up!". They left with both chucks, and two days later, UPS left replacement chucks at my back door. The new chucks were of a different make than the OEMs, and did make a significant improvement. They also are a much better fit on the spindle nose. I believe you'd be better off working finding the source of the vibration first, and then decide whether you still want to pour concrete.
 
I think one really quick way to eliminate the chuck as the source of vibration is to just remove the chuck and spin the lathe up to the speed you observed the vibration at. That should tell the story real quick and won't cost you a penny.

Joe Hynes
 
Not sure exactly which model you have, but my 1982 model 11x24 belt drive improved quite a bit with a better quality belt and a hard rubber pad between the motor and mount.
It's also much better sitting on rubber faced leveling pads than it ever was bolted down hard.
 
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