I did not think I could get it in there - too big.
Yes. Just as well. I have already started expending them! With the 4-jaw I just shimmed the workpiece.
The biggest ratio is about 3, the motor runs at 1725. The figure is also quoted by the Taig manufacturer.
Or I could make a counter-shaft. Or spend $588 on a 7x8 and tweak the controller - apparently one can get it from minimum 200 rpm down to 75. Or (drum roll!!) I could use my RedNeck lathe which goes down to 80 (once I got it on a stand and sorted out the tooling arrangement - no more than 3 years from now...).
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OK. Presumably there is a trade-off between the paper thickness and the need to adjust the tool height. But with my little post that should not be an issue.
Isn't everybody?
[...]
Done all of the above. Still squeals like a banshee. But it is better than it was with the original grind. Still have to keep backing out and clearing out the chips before the tool digs in and stops the spindle - even when it reaches the small diameter.
The washer was larger in diameter than the minor diameter of the threaded hole in the chuck back? Then mount it on a bolt and turn it down a bit until it does fit. If it will fit the bore through the chuck, that is small enough.
[ ... ]
Shimming the workpiece has two disadvantages, depending on how you do it all.
1) If they are kept behind the workpiece while turning, they are likely to fling out at high speed.
2) If they are tapped out after the jaws are tightened, the workpiece is likely to work its way in towards the chuck body as you turn.
You *could* make the shims in the form of turned rings which go around the last jaw step so there is nowhere for them to go even if the workpiece is no longer firmly gripping them.
O.K. I went down and checked (it was early enough this evening for me to find the mechanical tach and dig out the Taig to where I could run it.)
Here are the speeds which I get - run by a 1/10 HP motor whose "nameplate" (a sticky label) claims 1550 RPM.
The speeds which I measured are:
1) 580 RPM
2) 905 RPM
3) 1430 RPM
4) 3260 RPM
5) 5150 RPM
Total of five belt steps with that little tiny belt. :-)
So -- it does run faster than I thought, and my impression that it runs slower is probably because I seldom use it for anything large. I've got other lathes more suited for that, and use these for really small workpieces.
A DC motor, a Variac, and a rectifier would do a nice job there. If you really care about spindle speed precision, a servo motor and servo amplifier would be guilding the lilly. :-)
:-)
The countershaft might be a good idea. Two pulley steps (made on the Taig) -- one for about 1:1 ratio, and the other for about 6:1 ratio. Or -- if you could pick up a slower motor, make the pulleys identical, so they step up as much as they step down. A ratio of 2.45:1 (5:2 would be close enough) and a motor whose speed is about 600 RPM would be nice (though 900 RPM is going to be easier to find, I think. And bear in mind that the speeds I give above are with no slip. It will be slower with normal slip. Fore example, the 1650 RPM motor would be
1800 RPM with no slip. (900 with no slip becomes something like 825 RPM with slip, and 600 with no slip becomes 550 RPM with slip.) That
550 RPM would get you down to 316 RPM with your existing gearing.
But a DC motor a Variac, and a rectifier would be more flexible, giving you a much wider range of speeds, and the ability to change the speed in mid cut without having to stop the motor and change the belts.
Not much -- you can take out one shim about half the thickness of the paper (it will compress that much when you tighten the bolt holding the toolpost in place.)
:-)
Interesting. I get rather quiet parting even with 3" diameter stock -- but I'll probably be running at about 210 RPM.
That is another reason to consider the rear-mounted parting tool. Instead of digging in, it disengages a little when things flex.
Start looking at Craigslist or Freecycle for a treadmill. Most of them have a DC motor and controler, but I did find one with a AC motor and a varible speed pulley.
Look under Free and be patient.
Or look in Ebay for a small VFD and then locally for a small 3 phase motor. I just got a 56 frame three phase motor for $5 at a garage sale.
Are you complaining about them mostly being DC motors, or about the one AC and the VS pulley assembly? Both would be interesting to me Or did you get one assuming a DC motor, and when you got it home you discovered the VS pulley?
That would be a good way to go -- though I think that the DC motor would do better at really low speeds.
Of course -- I'm not the one looking for the slow speed motor, just one responding. :-)
Not complaining. Just commenting. I acquired several treadmill motors and found that one of them had a AC motor and a VS pulley. So if you want a DC motor, check how the speed is controled. Like you I found both interesting.
Cheap Variacs are a little hard to find. But a light dimmer or Router speed control will work and I think will give you somewhat better speed control than a Variac.
I don't, but even the bare bones are not a cheap option as I found out yesterday looking around eBay.
[...]
I was thinking of just getting two more Taig pulleys ($24.49) and making
*two* countershafts. The lowest speed would be just over 60 rpm. Even with just one pulley the speed would be under 200. And the theoretical maximum speed of 47,250 rpm. I wonder what the 3-jaw chuck sounds like at that speed...
The two questions that bother me about the concept of a countershaft are:
1) Is the 3M belt big enough withstand the torque at the lowest speeds? Or would one have to go to a completely different transmission for the final step (countershaft 2 to spindle), e.g. timing pulleys and belt?
2) If one were to make a pulley, how critical are the groove dimensions? The only pulley I made was the wooden one (and it works just fine) but the process can hardly be repeated with aluminium (or can it?)
And bear in mind that the speeds I give above are with no
Ah, with slip I can get down to zero, no problem...
That is clearly the preferred option but the prices I have seen so far really make it uneconomical.
Maybe I should reduce speed...:-)
Would it then get rid of the chatter by allowing an increased feed rate? At $5 that is the truly cheapest solution.
I have been looking for a while at garage sales and local auction. I will expand to Craigs list (where I follow other things). I saw one tread mill motor at the auction here but it was about twice the size of the Taig (2.5HP). I am told scroll saws are another possible source. Typically their motors are rated for about 160 watts but that should do for the Taig (if Don runs his off a 75W one).
I usually set the belt on my larger lathe to slip with nearly maximum hand pressure, on the little one to slip fairly easily. The leather belt changes length with humidity so I have to readjust it anyway. The motor and countershaft are on a swinging frame with a tension adjustment screw in series with a toggle linkage.
Here's an adjustable cam tensioner that's easy to make:
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bolt through the disk is 0.05" off center to pull or release the forged eyebolt in the slot. You could put it 1/4" off for a 1/2" throw to tighten or move the belt. Rotate the handle for fine adjustment, flip it to quickly tighten or loosen it.
Machinery's Handbook 23 gives the following groove geometry for a 4L vee belt: OD Angle Width 5.65 38 0.504
We discussed this here once, IIRC some posters used 35 degrees and
0.5" width for all diameters. You could try it and change the groove angle if the belt appears to be wearing quickly, but I suspect you can't drive a Taig hard enough to harm a belt. The heavily loaded pump drive vee belt on my tractor ran for 3 years and still looked OK when it failed with a broken cord. It ran on home-made pulleys.
You should *always* consider what might fly out when you could be in the path.
Note that I have never tried that design -- just thought of it as a possibility -- and one which does not require different size rings for each size of workpiece, since they are trapped by going around the jaw ends.
Someone else suggested a light dimmer which is typically quite inexpensive -- and as for motors -- a cheap hand held electric drill could be clamped onto a shaft in bearings to drive at a lower speed. Or -- you could salvage a motor out of a vacuum cleaner or a kitchen blender or anything else with a DC/universal motor. (Just look for brush holders to verify that it is not AC only -- and the holders may be hidden inside, as is common in cheap hand held electric drills.)
Two extra pulleys (and an extra belt) would make *one* countershaft, not two.
Hmm ... what *is* the sound of a 3-jaw chuck flying into pieces. That speed (if the motor could put out the needed torque) would certainly explode the chuck. A 12" chuck is considered dangerous at a bit over 3000 RPM IIRC.
I would suggest that you make a timing pulleys and belt for the step from the countershaft to the spindle to handle the extra torque. Look for pulleys for about a 6:1 ratio which will get you down near 100 RPM or a bit more.
The angle between the walls is critical, and the spacing has to be tight enough so the belt does not touch the bottom.
It could be -- but a lot of careful filing. And it will take a lot longer than doing it on the lathe. You will either need a compound set to make the proper angle for the walls, or a form tool ground to cut both angles at the same time. And I don't think that your machine can handle the amount of metal removal involved in a form tool, even for that small a belt groove.
Yes -- you can get down to zero -- but between zero and a bit below the nominal speed with slip you will have no torque to work with, so the descent from normal slip to zero will be very sudden.
An electric drill motor (a hand-held electric drill is called a "drill motor") with variable speed hooked to a shaft mounted in pulleys should do it -- until the drill motor burns out. They typically don't handle long run times well.
And increase rigidity too -- which is another feature of my 12" lathe which you don't have.
You would still have chatter -- it just would not be as destructive, and perhaps sound somewhat different.
Note that I don't do large diameter work on mine. I noticed that the hand pressure holding the mechanical tach in the end of the spindle would slow the spindle down a bit at the highest belt setting.
Also -- note that I have the WW (watchmaker's collet) spindle on the lathe, which has a smaller pulley, and higher speeds than the normal spindle does, so the speeds would be different on the standard spindle.
Mine is tensioned just by the motor weight which is clearly not enough. I have seen people make some cool arrangements like rails on which the motor slides. Incidentally my redNeck lathe will need something like that, too.
I am not sure I understand. How is the 4L belt dimension relevant to the Taig? Are you saying I should change the whole drive train to 4L? Isn't it a bit big for the machine?
As my old boss used to say: "You can recognize it only if you think of it."
1) I might be wrong but the DC motor controllers usually have a feed back which will increase the power in response to loading conditions. I do not see a light dimmer doing it.
2) A router speed regulator is a thought, however, typically these motors turn at 30,000 rpm give or take so major gearing would still be required. And I am still not sure about the feedback thing. Some routers have it built in now (EVS).
3) I have a DC motor from an old Sears drill sitting somewhere. As it stands it would also need the whole gear box to get the speed down to something useable. The speed regulation with it is basically the slow start. When it is turning slowly there is hardly any torque which brings me back to (1).
4) It is a thought to make a controller along the lines in (1) for the motor. However, given that the motor is a 12V one I usspect that the current at the lower speeds would be appreciable.
How is that? One pulley=motor. Belt to second pulley=countershaft 1 (reduction by factor of 3) Belt to third pulley=counteshaft 2 (reduction by factor of 9). Belt to spindle pulley (reduction by factor of 27). A single coutershaft would require pulley 2 and 3 to be on the same shaft with no reduction of speed between them.
Or 2 rpm if dropped from a second storey window. I know what sound a hockey puck travelling at 80 mph makes. I almost wish I did not...
Yes, that appears to be the consensus.
Agree. I have demonstrated it with the first parting tool. In any case your comments above re-timing pulley make this issue probably moot.
Well ... when anything is not firmly secured (and not just by friction between two pieces which *could* shift) consider what would happen should it slip. The better your imagination, the less likely you will be hurt in reality.
The fancy controllers do -- by various techniques, not all of which are immediately visible like an encoder or tach on the shaft. Some controllers apply power to the motor winding in pulses whose width are varied to change the power to the motor. During the moments between those pulses, the motor is acting as a generator, and the motor can see what the speed is by the voltage generated.
But consider things like an old Singer sewing machine motor and controller (such are are on the model 221 portable). It is simply a DC/universal motor and a foot pedal which controls the current to the motor (AC, but DC would work just as well). The foot pedal is simply a stack of blocks of resistance element between two electrodes. The harder you step on the pedal, the harder the blocks are pressed together, and the lower the resistance, so the faster the motor runs.
You don't *need* the kind of regulation which the fancy controllers give for this lathe. And you could use a pedal speed control from a Dremel (from before Dremels came with built-in speed controllers). I can't find the Dremel ones on eBay at the moment, but this looks as though it might work as well. It is poorly described, but I expect a controller for a DC/universal motor.
Ebay auction # 260291509189
The speed regulator is based on the speed a given motor is capable of. It won't make motors not designed for it turn at 30,000 RPM. Find a 120V motor which is closer to 1000-2000 RPM and see what happens.
This sounds good -- until you mention later that it is a 12V motor, not a 120V motor.
You want a drill which plugs directly into the AC line, not one which runs from batteries.
Oh -- you are thinking of two belts on each pulley except the end ones. That restricts you to combinations which don't need the same groove for both incoming and outgoing power. And I think the lowest speed with triple reduction would be both too slow for the size of the machine and those tiny belts could not handle the transmission of power over the last two stages.
Use timing belt pulleys. Figure the largest diameter which would clear the base when mounted directly on the spindle, and then look for the smallest pulley of the same pitch which will mount on the countershaft. At a guess, you might be able to get a 5" diameter pulley plus the belt on the spindle (make sure that it is available with a hub which matches the OD of the spindle at that end), and assuming 5 teeth per inch of circumference, that would be about 78 teeth. Then a smaller pulley with 12 teeth would give about a 6:1 reduction in a single pass.
O.K. Looking in McMaster Carr's web site, I find 1/2" wide belt pulleys with a 0.200" pitch (MXL series). Let's see the largest which will fit within 5" diameter.
The range for this size is 60 teeth max and 10 teeth minimum, or
So -- if you need to fit it on a 1/4" shaft, you will need at leat 14 teeth (60:14 ratio, or about 128 RPM for 550 RPM in.
If you can turn the end of the shaft down to 3/16", you get a full 6:1 ratio, or 91 RPM.
These (and others) are on McMaster Carr's catalog page 1044 via the web. (You'll also need to select a belt to fit including the proper spacing between pulleys.) The pulleys which I have listed are acetal plastic, and I would suggest that you go for the steel ones listed a bit later in the page for stronger gears. And you'll probably need to pin the hubs instead of just use setscrews to get enough strength with the small diameter shafts.
[ ... ]
A lot of smaller motors are "impedance protected", and can sit there stalled forever without letting out the magic smoke. :-)
On the DC side, I scored a high torque motor - 4 brushes at 90 degrees - that is 24V. Came out of a small elderly scooter. Some of these are beginning to come on line in lew of second/third/fourth generation 4 wheeler buggy/chair.
I cannot imagine that a lot of torque was required of Singer sewing machines. What hapens to torque at the lowest speeds?
I got one of them drills, too. But again, what happens to the torque at the low speed if using a rheostat? On mine there is a slow start feature which I take to be nothing more than a rheostat. I can stop the chuck by hand at the low speed.
I got a 13.6V 20A power supply - that's 1/3HP.
[...]
63 rpm. But I take the point about the torque.
This would mean turning the spindle shaft down to at least 3/8". I do not think this is possible. AFAIK the spindle is 5/8" with a 5/16" ID. Some of the plain bore pulleys have large enough bores but maximum of 24 teeth or so.
It is beginning to feel like trying to make a silk purse out of a sow's ear. Some limitations will have to be accepted I think.
I might have some Omniturn 90vt DC servo motors. Encoders are likely dead, but will run fine. Bout 3" in diameter, about 8" long with a 1/2" shaft about 2" long.
Free but for the shipping if I can find em.
They are about 1/2 hp IRC.
Gunner
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Why would you want to change the rest of the transmission to the Taig style? An oversized motor and belts will cost you a little extra electricity but you can easily make them slip to not overstress the lathe.
1/2" pulleys and 3/4/5L vee belts are the only drive components readily available from hardware stores on weekends, at least around here. And they work well with small electric and gas motors. If you build drives from surplus rather than carefully engineering them, it's very helpful to have very few variations of shaft size and belt type, so you can recycle the growing collection of spares when you move on to air compressors and bandsaws.
That someone was me. Light dimmers work pretty well. They are a stiffer source than a variac, and I believe the back emf from the motor affects when the triac fires. Another source for universal motors is WeedWackers. I bought one at a garage sale recently for $5.
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