Quick unlocking of compound base on lathe

I see that my lathe has a collar that fits over the base of the
compound. There are two nuts to tighten or loosen the collar, allowing
the compound to turn. Has anyone used a lever like on a mill table to
tighten the collar down?
Reply to
Louis Ohland
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Hi, louis. I see no one has replied to your question, yet, so will offer my opinion.
My Emco lathe has the compound clamped to the cross slide with just such a ring/collar and two bolts that fit into the "T" slots on the cross slide. For my lathe, anyway, only real nuts will work, as they have to be completely removed to remove the compound and locate it to the second position on the cross slide. It also has to be completely removed to use the cross slide table with the milling head. The vice then mounts to the cross slide using 4 bolts/nuts in the "T" slots. Also completely removed to mount the cutoff tool holder.
Some years ago, I did replace the single nut holding the tool holder to the compound with a new nut with a 5 inch handle. Makes moving and removing the tool holder much simpler and quicker.
Do you also have an EMCO, or did some other company copy the design?
Best regards, Paul, KD7HB Crooked River Ranch, Oregon
Reply to
co_farmer
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Is it a copy of the EMCO? Dunno, but the Chinese seem to be the T2 kind, where they can copy someone and then kill them, er, produce copies to gain market share...
My lathe uses the two T slots as well. Unfortunately, the two clamping nuts are not so big, maybe 1/4" across. They are cunningly tucked under the compound and the one to the front is a beech to get to if the compound is anything but fully to the rear of travel.
Reply to
Louis Ohland
Did you not get a wrench to fit all the nuts on the machine? A rather thin double open ended metric wrench came with mine and somewhere I got another small open end wrench to fit the nuts under the compound. Yes, it is a tight fit sometimes, but the wrenches both work in all compound positions.
Your lathe looks kind of like the Emco. Hard to be sure from a single photo.
Paul
Reply to
co_farmer
I wish they made lathes that way with a lever locking compound, but i've been happy with the Southbend solution which uses two hex set screws, it's reasonable easy to access with a T handled hex tool.
Reply to
Tony
After looking at the chin-glese schematics, it looks like the compound sits on the surface of the saddle with the only thing holding it down being the two nuts through the hold down collar. If the schematics are close, those two shafts coming up from the T-slot nuts are 8mm. Looks tempting to make new T-slot nuts with 1/4x24 threads and a 90 degree handle. Take up most of the slack in the screw before sliding the compound back on. Then a quarter turn on either handle to lock the compound.
Reply to
Louis Ohland
Hi Louis,
This collar is a weak point on the 9x20 lathes.
I've been toying with making my own replacement, a bit different than the other solutions I've seen so far.
It would look something like this:
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I just made a rough draft for you to see my idea. It needs to be around 1/2 to 5/8 inch thick. You would have to measure the distance from you compound to the cross slide for an exact measurement on thickness. I recall you mentioning that the new tool holder you installed is a bit too high. After removing the degree ring (necessary mod) from the bottom of the round column you may be able to move the compound down a slight amount too.
The slot could be cut so that the cross bolt is tightened from the right hand side (or left) rather than the front as in my crude diagram. I'm not too sure where the optimum position for it may be yet.
This should make for a lot more support/rigidity on the front of the compound assembly. You would get your easy to adjust compound angle too, with just one hex head cap-bolt.
Downside is losing the degree ring. A lot of guys already use a separate protractor for setting the angle anyway and I would like to have the extra support/rigidity myself.
I think this should work okay, but I haven't tried it yet and could easily be missing some obvious problem with it...
Reply to
Leon Fisk
Hi Leon, I'd be very interested to hear how your clamp design performs.
You're correct that the 9x20 compound collar/locking/mounting plate is the weakest point on these models, as far as cutting tool rigidity is concerned.
I like socket head cap screws as much as anyone else, but they're a problem in the presence of chips (particularly facing upward), and more-so when cutting lube is used.
I'd seen the Bedair and several other 4-bolt solutions for the compound mounting plate several years ago, and concluded that I'd try to come up with a plate that would offer some support to the cylindrical portion of the compound (the round column at the bottom of the compound base casting).
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This base plate can be machined on the 9x20 lathe using the supplied 4-jaw chuck (although I used a rotary table and mill of a 3in1 machine to make the crescent-shaped undercuts in the corners).
With the hold-down bolts loosened, there is some resistance felt when adjusting the angle of the compound, so it's not loose like the original plate. Keeping the fit very close for the hole diameter and the counterbores for the degree wheel/disk will make the compound very much more rigid in use.
While using the new compound plate, I found that it's not neccessary to loosen all of the nuts to change the position of the compound. The fit is not so tight that you'd be inclined to make a huge wrench to fit the compound, just to adjust it. Additionally, this plate doesn't change the height of the compound.
I had considered cutting out a section between the "front" bolt holes (closest to the operator) to leave the degree wheel exposed, but figured I'd add it later if it was needed. The other method I wanted to use for seeing the degrees position would be to mark the degrees on the tapered "wall" of the mounting plate, and use a brass disk between the compound base and the top of the wall/shoulder with a tick mark, with the disk secured to the compound base.
I left the pin that protrudes from the compound base intact. This pin drops into the 2 blind holes in the top face of the cross slide table, and I didn't see any need to remove it, since it may actually contribute a little in the way of rigidity.
I contemplated a lever-locking solution for the compound, but there is such a height limitation to work within, it seemed that fabricating a lever-lock would've been a much more complicated way to go. I've seen a very reliable design of a lever-lock on a Gorton rotary table that I have. It doesn't lock around the circumference of a feature, but uses a threaded post to apply a vertical force at the center "spindle" portion of the table, to pull the table down tightly on the base casting. A very reliable design, but it may prove difficult to fit into a 5/8" space.
WB ......... metalworking projects
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Reply to
Wild_Bill
Those are a couple of the ones I've looked over and considered making too.
My compound is off right now and I took a quick look at it again last night. My only fear with my suggested design is whether there would be enough clamping pressure to keep the compound from creeping in use. It would take a bit more work but you could leave the degree plate in place and counter sink the bottom for it. That would keep it captive and if you kept the tolerances tight would help keep it from working loose. I kind of like the idea being able to drop it into the holder though. You could make other accessories to drop in then too.
My other thought is to turn an adaptor to replace the degree plate that is made of steel and the same diameter as the top of the column. This would provide more clamping service to get a hold of.
I've been toying with this for awhile now and will probably try making it unless someone points out the folly in it. It seems like an obvious solution/method and I wonder why nobody has tried it. Usually that means it is a bad idea for some reason or another :)
I'll let you know how it works out if I ever get around to it. First I need to get the lathe running. It only took me 3 weeks to get it out of the crate and mounted on a bench. That was last April... There is still something wrong with the motor/belt area. I have to walk the belt on/off even with the tension released. There are two different belt lengths sold for it and I have the shorter version. I tried searching some, but couldn't find any info on why two different length belts are used. Only thing I can figure is that it depends on which motor is sold with it (shrug).
I am cheap and loath the idea of buying the longer belt just yet.
Reply to
Leon Fisk
I hadn't thought of your design being useful as a sort of universal mounting plate, and that's a neat idea.
I procrastinated making my 4-bolt plate too, and one of the other reasons that made it seem definite was that the T-slots of the cross table aren't very strong, and using 4 T-nuts was a much better mounting solution.
I hadn't heard about the 2 different sized belts, but I'd most likely get one locally instead of ordering it from one of the lathe distributors. I had read of the belts rolling over and causing other problems. Mine didn't cause those problems, and the original is still on the lathe. I did notice that the tensioning lever needed some attention, while I was setting up the machine though. The pivot point was really sloppy where it passed thru the plate, and I added a shim washer there, and bought a new retaining snap-ring of better quality.
Somewhere in one of the Dropbox archives, there is the threading chart for the 9x20 lathes, but I didn't find it right now. Someone on the Yahoo group had come up with a chart that shows a lot of thread pitches that are possible on the 9x20 which aren't shown in the user manuals, including the metric spindle thread on most models (except the Jet brand, which don't use a metric thread, I guess).
WB ......... metalworking projects
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Reply to
Wild_Bill
I've found/saved several thread charts already. If you need/want one I'll gladly squirt them off in your direction.
On Bedair's website he makes mention of cutting down one of the larger gears shoulder so that the cir-clip can hold it in place. Otherwise it is too thick. I think that is the gear you need for turning the thread on the spindle nose. Pretty sure that is mentioned on the page where he makes a backing plate for a new 3-jaw chuck. Here it is, see:
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He has one of the thread charts too:
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I asked Steve about the different belt sizes and he didn't know why either (he has a DC motor now). My idea about different motors being used was as good as any. Take a look at this page and then you will know about as much as I do about it:
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Mine is brand new (Harbor Freight 9x20) and has never been run yet. The belt measures 705mm in length (I checked it several times :). It is as tight as I think it should be WITHOUT the tension being drawn down on it.
I've read some stuff about other people having trouble with the tension pulley too. One guy ruined several belts before he figured out the tension pulley wasn't lining up right (yipes!). I'll remember to check that area out good when I get to that point.
I'll keep you in mind and let you know how it goes if I ever get around to making one.
Reply to
Leon Fisk
Thanks again Leon, yes if you wouldn't mind, I'd like to see the threading charts. I believe my Yahoo mail account (without the xspam) will accept them.
I've found that taking the time to examine and adjust/refit a machine prior to setting it up, is well worth the effort and time.. another good example besides the 9x20 lathe was the 4x6 bandsaw. I had the saw apart for quite a while before I actually turned it on.. there were a lot of little things that would've caused me to stop using it if I hadn't fixed them before I started using it.
WB ......... metalworking projects
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Reply to
Wild_Bill

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