Re: LHT-25B - Small Turret Lathe

... I'll mostly run standard 5C collets, but having a chuck may save the day at some point. The lathe did also come with an unused/uncut pie collet. I'm not sure if I am looking forward to the day when that is the answer to a problem or not.

-- Bob La Londe CNC Molds N Stuff

-------- My limited experience with 5C pot collets is that all but the shortest tubing, bushings etc should be held in axially as well by the tailstock, perhaps with a pipe center or large fender washer, and trimmed to length in the better restrained grip of a 6-jaw. I save hole saw and Greenlee cutouts for such purposes.

I was given a "Precise SC 42" CNC spindle by a scrap dealer. Fischer USA emailed me the manual for it, which assumes it's connected to their controller and doesn't mention the motor drive specs. Do you have any experience or suggestions concerning their electrical requirements? I'd be mounting it on the lathe in a milling attachment to do the indexed milling / drilling on large chucked work that I presently do on smaller pieces in a collet fixture on the mill.

Most turret lathes don't have a proper tailstock. The turret is the tail stocks. That being said I "also" have a removable tailstock turret I use in the little 8.5x18 Harbor Freight lathe. I do have a proper set-tru 6 jaw that I almost always leave on the 14x40 Precision Mathews.

I don't really know what that is? Picture? Sounds like a small high speed high frequency 3 phase spindle from what I have read.

Base voltage is probably at max frequency, but I wouldn't know for sure. For example most of my high speed spindles are 230V at 400hz. You can probably get that from the manual. I only found a couple mentions on line with queries similar to yours. If you are not sure of the wires its pretty simple to find out. If it has four wires one of them is likely case ground and the other three are the legs of the windings. After that you would need to find rotation. There is a meter that can help you find phase rotation. I have one, but I don't know how to use that feature. I've always just the power on and off with any 3 phase motor and if it runs backwards swapped any two leg leads.

Since I can't find specific information on exactly what it is I have to guess that if there are other leads they would be for overheat sensor, collet closed sensor, etc.

!!!Caution!!! Some high speed spindles caution that you can damage them by running them backwards. (and of course you can damage some kinds of pumps if run backwards.)

I probably should make/finish a side milling spindle for the bigger lathe one of these days.. and some indexing discs to go on the outboard side.

While digging around I found a shop-made Dremel adapter that fits the tool holder on the AA lathe for grinding, and I'd forgotten modifying it to also go on the SB, so I don't need to make the 1/8" capacity CNC spindle work. The Dremel can spot drill indexed holes to locate and complete on the mill.

The lathe indexing disk is similar to this, bored to fit behind a thread-on chuck or 5C spindle thread protector.

I'd want to index most on my 14x40 which has a D1-5 Spindle nose. I can't put anything between that and the adapter plate. Technically I could put something between an adapter plate and a chuck, but I would prefer to index at the back of the head where it is completely out of the way. I need to make a spider for it someday as well. Probably make both setups at the same time. I'd just CNC the indexing plate on one of the mills for whatever I needed. I am sure it will be "close enough." If I need to try to chase decimal plates I might make it on the big manual knee mill with the DRO instead. I don't know how I would QC it though. I guess the end part would have to be the QC.

Even small ones are expensive if you get quality . I got a screamin' good deal on that one . The piece of steel I bought for the back plate cost me more than the chuck .

I'd want to index most on my 14x40 which has a D1-5 Spindle nose. I can't put anything between that and the adapter plate. Technically I could put something between an adapter plate and a chuck, but I would prefer to index at the back of the head where it is completely out of the way. I need to make a spider for it someday as well. Probably make both setups at the same time. I'd just CNC the indexing plate on one of the mills for whatever I needed. I am sure it will be "close enough." If I need to try to chase decimal plates I might make it on the big manual knee mill with the DRO instead. I don't know how I would QC it though. I guess the end part would have to be the QC.

-- Bob La Londe CNC Molds N Stuff

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I seriously considered drilling index holes in the rim of the backplates if I could mount them on my dividing head accurately enough. The 4" and smaller chucks on 5C mounts can index in milling fixtures. A larger diameter index disk with an alignment recess could be screwed to a D1-5 backplate.

I needed to index 68 for a steering sector gear and 13 for a motorcycle drive sprocket, neither matching an index disk. I used a 52 tooth change gear from the AA lathe for 13, and cut the spline slots slightly too narrow so the hardened sprocket shaved them to a snug press fit.

I think the QC process for an index disk is to turn two pins to a light press fit in the holes and measure across adjacent pairs of them with your best mike, similar to using toolmakers buttons for jig boring accuracy. Only the differences between measurements matters.

I don't see why it would any any harder to indicate in than anything else you put on it. Face up, and indicate in center of rotation of disc. Face right (or left) and indicate in perpendicular to travel. Indicate center with half function. Drill, ream, rotate, Drill, ream, rotate,Drill, ream, rotate... it wouldn't be hard. Just tedious.

USE A STUB (screw machine length) DRILL.

You have an Indicol (or clone or home made holder) and a test indicator right?

I don't know how I would QC it though. I guess the end part would have to be the QC.

-------------------------------- One of the old manual methods Holtzapffel mentioned to create an index plate is to step dividers around a scribed circle and keep adjusting them until the last step equals the first. That task could consume a boy's entire apprenticeship time.

I made a graduated dial for the crossfeed of my AA lathe, which has a

Later I was tying up a military satellite uplink with a test pattern of 10 million bits at 2400 per second. When the manager asked when I would be done that dividing exercise let me mentally figure the test would run for 4,166.7 seconds, or 1 hour, 9 minutes and 26.7 seconds (3600+540+26.7). He gave up trying to confirm it on his calculator.

Afterwards I was assigned more challenging and interesting design tasks, interfacing an atomic clock oscillator to an embedded computer and designing a 16 bit data acquisition system for a Macintosh, good jobs for a technician without an EE degree.

You have an Indicol (or clone or home made holder) and a test indicator right?

-- Bob La Londe

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I have a shop-made indicator holder customized to the Clausing's spindle diameter and a B&S BesTest graduated to 0.00005". Mostly they tell me that my machines are very old.

I don't see why it would any any harder to indicate in than anything else you put on it. Face up, and indicate in center of rotation of disc. Face right (or left) and indicate in perpendicular to travel. Indicate center with half function. Drill, ream, rotate, Drill, ream, rotate,Drill, ream, rotate... it wouldn't be hard. Just tedious.

USE A STUB (screw machine length) DRILL.

You have an Indicol (or clone or home made holder) and a test indicator right?

-- Bob La Londe

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The issue isn't indicating, it's clamping a large threaded backplate (or similar) to my hobby-sized indexing equipment. The Clausing's spindle to table clearance limits the height of work pieces and table accessories. I located the old sector gear for setup and then the blank for cutting on a

A Clausing is very nice for making -small- parts. An RF-31 has a larger work envelope. This is the upgraded model with a taller column. Notice that it's drilling with a collet instead of,. a chuck, which I sometimes have to do for clearance.

You can make fairly accurate parts on a sloppy machine. DROs and gibb locks help a lot with that.

Machinery's hand book trig tables, sine plate, tilt the head. Nah, now its getting hard. Not impossible. Just hard. LOL. The thing is once you get it dialed in its still just rotate drill ream, rotate drill ream...Oh, yeah, rotate in only one direction if you are really chasing decimal places.

I drill with a collet for the same reason all the time even on this machine.

I'm not a fan of Grizzly, but this machine is a beast. It was also only $19,995 when I bought mine.

In fact I have made my own split collets for sizes like #7 and #21 to slip inside the native R8 spindle collets. I have also moved the head off to one side and hung the part out past the table, clamped to the face of a right angle plate. This adds a couple feet to the height of a part I can drill. I prefer not to move the head around if I don't have to though. Hence why I use collets sometimes instead of the Tegara integrated shank drill chuck.

-------------------------------- Since I modify Grade 5 and 8 bolts fairly often I made a 3/8"-16 3-part split collet to clamp the threads straight while machining the usually less straight shank and head. The best version has O rings in grooves at the ends that keep it together and let a bolt or threaded rod be pushed instead of screwed in. Less commonly modified sizes have solid threaded bushings to allow turning a root depth pilot and tapered aligner on the ends, a great help outdoors where a dropped screw can be lost in grass / leaves or slide into the gutter.

The Clausing head can extend and swing like a Bridgeport, except for Nod. Tramming it square afterwards is difficult because the clamp screws shift the head when tightened, on mine the front and rear screws shift differently.

I position the spindle where an end mill will barely pass behind the fixed vise jaw.

A Clausing (Johansson) is similar to the original M head Bridgeport, which I've seen in this museum.

This is a currently available knee mill similar to the Clausing and M head, with R8 instead of their 1/2" 2MT or 7B&S collets: