I was going to make a quick and dirty dividing head to use with my Taig chucks on my X2 mill.
I thought I would basically run a shaft through a block of aluminum with 3/4-16 thread on one end and a dividing plate on the other. Then I thought: What shaft? What bearings?
Primary concerns here are not the rotation loads but absence of radial and axial movement of the shaft.
I am not sure what engineering principles apply. Would an aluminum shaft with a slip fit through a hole in the aluminum block suffice? Presumably a steel shaft would wear out the aluminum. Would it be better to use a steel shaft with bronze bushings? Ball-bearings seem a bit of an overkill.
Maybe by the time I think this through I will find it expedient to get a Taig headstock for $60+ and use it as a base for the project (a common approach, apparently). However, I would still like to know what is the correct approach if building from scratch.
I bought two used ones for ~$50 each and mounted one on an angle plate with the axis vertical. If necessary the second can serve as a tailstock to steady a long shaft, like the splined pulley broach I have to make soon.
The Spin Indexer is less rigid but can be set to 1 degree with the vernier holes on the top:
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A chuck for them:
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Then there's this:
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The rotation load is VERY important when milling if the work diameter is larger than the shaft clamp. You can arrange a clamp that secures the work directly to the mill table at the cost of inconvenience.
Current Home Shop Machinist has a how-to for a cheapie indexer using change wheels on an Atlas 6". I've seen similar using just a block of scrapbox steel and a shaft with suitable arrangements for attaching the gears. No bearings used besides a good running fit. A spring- loaded plunger to fit the gaps in the teeth does the indexing. Probably an afternoon's project. Or you can just get a 5C indexing block set and have at it.
Actually -- a polished steel shaft would be a better bearing with the aluminum housing than an al-al interface. keep it lubed, of course.
How much load forces are you expecting?
Or -- perhaps get an old Unimat or Emco-Maier dividing head, if you need no more than 60 divisions.
Of course -- the Unimat ones go for crazy money these days, if you can find them on eBay at all. People are *collecting* these things instead of using them. :-)
I have looked at all of those at one time or another. I rejected the spin indexer because of the 5C collets. The chuck adds $100 to the cost. The rotary tables have the same problem.
Right now the job is to drill several cross holes in round stock at precise but not necessarily outlandish angles. I was also trying to use what was in the drawer. Maybe even learn how to thread on a lathe :-)
I was going to buy the Grizzly rapid indexer but both Grizzly and Busy Bee are out of stock. Also at 6" it would probably bee a tad too big for my X2.
I suppose an option would be a spin indexer, a 3/4" collet holding a short shaft with 3/4"-16 thread and a Taig chuck. Now that you made me look at things again I should consider it.
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I do most cross drilling of round parts in the lathe with a motorized drill spindle that fits the QCTP at lathe centre line height.
The spindle is aligned parallel to the chuck face with a 123 block and is driven by a windshield wiper motor at 30VDC or so, developing about
1/4 HP.
Even used this for light milling when I needed a small triangular cross section pin.
For cross drilling you don't even need a lathe spindle lock; indexing is done using the chuck jaws with a spacer pin against the bed ways. For more than 6 divisions I have used a protractor with bubble level.
Not super accurate but it gives acceptable results very quickly with a minimum of set-ups.
I used to make a lot of model steam fittings and stuff that required cross holes. I quickly got sick and tired of the set-ups required to do this and built that motorized spindle using bearings at hand with a custom machined mounting to directly fit the quick-change tool holder.
While not in every-day use it has saved a lot of time and aggravation over the years.
Similarly I made a Dremel tool holder from an upright rectangle of aluminum plate thicker than the compound slot.
The lower edge was stepped to fit snugly into the slot. A vertical hole near the right edge takes the hold-down made from a carriage bolt.
I set the compound parallel to the ways and bored a snug hole at center height for the Dremel nose. If the hole had been a looser fit I could have slotted the block to let the carriage bolt clamp the Dremel. The compound feed screw runs a drill bit straight in or a grinding wheel at the compound's angle.
My next project of that type is to adapt a laminate trimmer to the larger lathe.
I have been looking at the similar arrangement and have not ruled it out completely:
1) Do it on the Taig. Make a divider plate which should be relatively simple and the spindle lock is easier to make than on the 9x20. Adapt one of the toolholders (or make a brand new one) for the Dremel flex shaft. The only thing that put me off that is the 1/8" or so limit of the Dremel. In fact the whole concept started me thinking along the lines of buying a new Taig headstock and adapting it as a dividing head - then I could also mill etc. on the X2.
2) Do it on the 9x20. It should not be difficult to make a clamp for the Dremel flex shaft here either. The cons are no spindle lock and the drill size limit as above. I am not sure that I grasp the concept of the "spacer pin". However, if I found a way to lock the spindle in any position one could use a magnetic protractor gauge which I have found eminently useful in other applications to set the angles.
3) Do it on the *wood lathe* - that one has not only a spindle lock but an in-built dividing plate with 72 positions. Again the Dremel holder should be easy to adapt to the tool rest banjo, but the above limitations apply. Also would have to get a new chuck for the 1"-8 spindle. OTOH how easy would it be to get one of those MT2/plain adaptors and cut 3/4"-16 thread on it and use it with the Taig chucks?
BTW I have been looking around at the spin indexers: Somebody on another forum posted pictures of the indexer which he adapted for ER40 collets! I thought it was a particularly smart move but could not find a description of how he did it.
Many options could result in paralysis by analysis :-) However, as the job is not imminent, it is good to explore them.
Instead of locking the spindle you can clamp the divider plate. The leverage would be better. The laminate trimmer has 1/4" collets and better mounting surfaces than a die grinder. Speed control:
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Buy one of these, tighten a nut on it and thread the nut:
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''/Detail.bokI'd face the arbor flange side of the nut first and saw a slot so it could be removed if it stays in the chuck. Or leave a hex flange on the nut.
Why bother unless you already have the ER collets? 5C collets are as cheap as any other and are the standard for square and hex collet blocks, end mill grinding fixtures etc.
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Those are fine for cross-drilling a shaft or milling a square or hex head.
You could pick a few appropriate sizes for your rod stock and collets, you don't need a full set. I chose 1/2" and 1" for expensive metal like O-1, 12L14, 303, 4142 etc.
Today there are more options than there were when I built my tooling. I found the dremel tool speed too high for effective drilling of steel.
The spacer pin (or bar) is a length of rod that I place between the bottom edge of the horizontal chuck jaw and the flat of the lathe bed; this makes for quick-and-dirty indexing. By careful choice of this spacer you can get 6 divisions quickly depending on your lathe's design. Certainly 3 div's are easy and a cross hole is a cinch.
Cross drilling does not impose a rotational force on the work piece and I found that clamping of the lathe spindle, for this operation, is not necessary. If you are concerned simply hold the spindle, by hand, against the spacer pin mentioned above.
My drilling spindle runs on 2 ball bearings of 3/8" bore and mounts a threaded 1/4" capacity drill chuck. It is driven by a windshield wiper motor through a 3-1 reduction timing belt.
Built into the lathe bench is a variable AC and DC power supply controlled by a Variac auto transformer. This is a permanent set-up as I use this for other work and experiments. The variable AC is fed into a step-down transformer, rectified and smoothed with big capacitors. This transformer can handle up to 40 Amps or so and can supply up to 30 volts DC. Most wiper motors are very robust and reliable and can handle this easily. In the last decade or so really powerful radiator fan motors have become available and I would use one of these if I were to do this again.
Once you have this device you will be amazed how easily you can carry out what is otherwise a tedious operation.
For a small lathe a flexible shaft driven hand piece held in a dedicated QCTH would be the way to go. Take the time to make a nice tool that will provide use and enjoyment for a life time.
As a guide to the tool holder simply look at the commercial toolholders that carry a fixed drill chuck. Extend the back side of this holder by some measure and drill & bore it to take 2 ball bearings or the hand piece, where the drill chuck is mounted.
By planning ahead this tool can be used for cross and axial offset drilling ie holes in a bolt circle. For this though a lathe spindle clamp is advisable.
Actually that is the way I was planning to do it. A pin through one of the holes on the plate.
What are you going to use it for?
OK. Is an adaptor with an internal thread 1"-8 (for the lathe spindle) and 3/4" -16 outside thread (for the chuck0 an option? I was wondering how to preserve the through hole.
The benefit is the extended range of grip. Much of the stuff I use is not within the 0.003" or so of the 5C collet size.
The 10th picture down. From what I read people use these blocks more than anything else. I even thought of them and a single 3/4" 5C collet with a threaded shaft through it to match the Taig chucks.
Picture No. 21 is probably one of the cheaper combinations I have looked at: Spin indexer and a 5C chuck. My concern there was that I would run out of space on the X2 table.
I need to visualize this. There is a hole directly under the chuck on my lathe. I guess some kind of a wooden block etc. might do.
I was thinking of making a big handle for my 9x20 and attach it to the other side of the spindle. I thought it would help with threading amongst other things. I should be able to think of ways to immobilize the handle in various positions.
I don't mind dividing head but I always get the first round and then the rest of you guys can have her after that.
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I was going to make a quick and dirty dividing head to use with my Taig chucks on my X2 mill.
I thought I would basically run a shaft through a block of aluminum with 3/4-16 thread on one end and a dividing plate on the other. Then I thought: What shaft? What bearings?
Primary concerns here are not the rotation loads but absence of radial and axial movement of the shaft.
I am not sure what engineering principles apply. Would an aluminum shaft with a slip fit through a hole in the aluminum block suffice? Presumably a steel shaft would wear out the aluminum. Would it be better to use a steel shaft with bronze bushings? Ball-bearings seem a bit of an overkill.
Maybe by the time I think this through I will find it expedient to get a Taig headstock for $60+ and use it as a base for the project (a common approach, apparently). However, I would still like to know what is the correct approach if building from scratch.
A bigger Dremel that takes 1/4" shank carbide burrs. Though so far I've confined all grinding to the smaller, less valuable AA lathe, which has a 1/2" - 20 drill chuck on its spindle. They are safer (I think) to file and sand near than a 3 or 4 jaw chuck. I recently ground 1/8" music wire into a router bit to deepen the O-ring groove on a hydraulic pump.
I'd sooner make a new backplate. Several attempts at mounting a 1-1/2"
- 8 threaded Jacobs 58B chuck to my 2-1/4" - 8 spindle haven't been all I could ask for. Maybe the chuck itself isn't rigid enough to turn a good finish.
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it fits nicely on an Enco version of these:
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Some discussion:
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If you made parts from standard-sized stock you could leave it attached to the rod, or at least a short plug on one end.
If you can find one, the Sherline 5C 4-jaw protrudes less than half as far. The body is 1.25" thick:
Try this ASCII drawing: (view with a fixed pitch font like Courier to avoid drawing distortion):
______ / YY\ Octagon shape is the round chuck. / _YY \ |XXX/ \ | XXX is jaw which is supported |XXX\__/ | # ZZ / YYY & ZZZ are the other two jaws. #\_____Z/ # #### is the spacer supporting the chuck jaw ^_# ^__ WWW WWW WWW is the cross-section of the lathe bed and ways WW WW WWWWWWWWW Smaller hexagon is the hole through the chuck and spindle WWWWWWWWW WWW WWW
Make sure that the handle can be detached or your lathe will dance all over (and off) the workbench from the imbalance under power.
Besides a variac for universal motor variable speed, the inexpensive triac/diac-type Router Speed Control units sold by HF and others (maybe $12 on sale) might be a good alternative. IIRC, the user manual states that the speed control units are for series field windings, but I haven't read it recently.
I haven't tried one, but the laminate trimmer motor may also work well with a light/med duty versions of Minarik or KB DC controllers, which would likely provide better speed regulation (depending upon model and features), if they're compatible.
Just tried both, the Variac turns down slower but there isn't much difference in the low-speed torque (or lack of it). I used a lamp dimmer, not a router control.
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