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Member postings for John Haine

Here is a list of all the postings John Haine has made in our forums. Click on a thread name to jump to the thread.

Thread: Aging fingers
24/08/2021 09:52:18

I think copper bracelets, magnets etc are essentially placebos. What does work is massaging Ibuleve or a similar ibuprofen gel into hands. Reduces inflammation and pain.

Thread: hi new here from ely
24/08/2021 08:37:28

Excellent!

Thread: Myford super 7 with gearbox - leadscrew stopped turning
24/08/2021 08:33:03

Check that the tumbler reverse hasn't become disengaged (lever in mid position)?

Thread: hi new here from ely
23/08/2021 10:09:46

I'm sure the mods would be quick to remove the links if contrary to their policy! Post away as far as I'm concerned. Ely is alas a bit far for me.

Thread: 3ph motor running slow
22/08/2021 12:50:28

Synchronous motors in large sizes are very rare. The easiest way to check is to look at the rotor. A synchronous motor will either have pronounced "poles" on the rotor, or have a plain magnetic steel rotor if it's a hysteresis type motor. This Wikipedia article has photos of squirrel cage rotors. One frequent giveaway is to look at the end of the rotor, which you may be able to see if the end caps have cooling ports in them. You usually see the riveted ends of the conductor bars in the rotor. Another giveaway is the speed - you said it should be running at 2160 rpm but a synchronous motor would run at 3000 rpm on 50 Hz! Capacitors work with true 2-phase motors designed for capacitor run but are unlikely to work with 3 phase as the windings are at 120* rather than 90*, and all the windings are identical. One thing to watch out for if you have rewired the motor is that the winding senses are correct - sometimes people get one winding reversed and the motor runs rough and torque is low. If the internal wires were colour coded and the diagram showed the colours this is hard to get wrong though.

If you have a VFD then just use it!

22/08/2021 12:17:09

Seeing you are in the Netherlands then maybe you could find a local supplier to avoid the Brexit nightmare, but NT could advise perhaps.

22/08/2021 12:14:54

To be pedantic, I assume it's an induction motor not synchronous?

I think you will need a proper 230V 3 phase supply rather than a capacitor kluge, which probably isn't giving anything like the right phase angles so you are not getting much torque.

I assume that the schematic on the motor was for a star (380V) to delta (230V) conversion? That is still 3 phase.

Best bet is to buy a low cost VFD which will generate true 3 phase and give you variable speed. Newton Tesla are a good supplier and I have two IMO low power inverters, one on my mill running a half horsepower motor and the other a smaller motor on a Unimat. IMO aren't the cheapest but NT's support is great. Many people here have bought cheaper inverters from eBay and a reliable brand seems to be Huanyang though the instructions are not easy to follow I believe, but plenty of people who can advise.

Thread: cutting spur gears on a mill
22/08/2021 11:23:01

I've experimented with making a particular sort of helical gear - "helical lever" - which have simple straight sided teeth - they were used by a Victorian clockmaker and can realise large reductions in one stage as you can make one-tooth pinions. I believe that you can hob helical involute gears with a standard hob. From what I recall -

  • The "helical pitch" which is measured orthogonal to the teeth is the same as that of the hob.
  • The circumferential pitch is increased by a factor 1/cos(helix angle) so the diameter of the gear has to increase as well (as does that of the mating gear of course), by the same factor, to fit in all the teeth.
  • Looking at the tooth form along the helix angle it is involute because that's what the hob cuts. This is also what is "seen" by the mating tooth of the other gear which is also helical. It may not be the same as the profile of a cross-section of the tooth.
  • You have to angle the hob by whatever its own helix angle is to cut a straight tooth - for a helical tooth you add or subtract the helix angle depending on the handedness you want.
Thread: SIEG C0 Auto feeder S/N:10153
22/08/2021 10:58:55

I just checked and the U3 leadscrew is 8mm but of course a LH thread.

pxl_20210822_092515547.jpg

This would probably be a suitable motor. It is this type available on eBay, though I bought a couple years ago and haven't used them. Size is 36mm dia x 60mm L. Shaft 5mm dia with flat, 8mm long. Speed at 16V supply 340 RPM so would need another reduction stage probably as well as a speed control such as the ubiquitous MFA one. There are lots of other similar motors around. The U3 drive is 0.02mm/rev, so at 500 rpm of the h/s that's 10mm/min. As the l/s pitch is 1mm (I assume) the leadscrew will be doing 10rpm. So driving it direct from the motor you would need 16x10/340 = ~0.5V average which would be right at the low end for the speed control. Hence the desirability of an addition reduction. Motors are available with significantly greater reduction. (Note to Mods: these links are given as examples to show what's available - if you delete them I will be disgusted.)

I think it would be easiest to position the motor at the handwheel end with a modified or new handwheel, possibly with a pin clutch of some sort or a slippable belt. Assuming the C0 uses the same fork and tongue arrangement as the U3 at the headstock end, making a stable connection to the motor could be a bit tricky.

A stepper would be equally good though bigger and more expensive but a modern size 23 one would have plenty of torque even for direct drive. I use a rather old fashioned stepper on my coil winder to drive an M6 leadscrew and there is quite a lot of friction but it works fine. If you used a stepper it's a short step (sorry!) to fitting a digital leadscrew system!

If you did want to use a worm reduction you could perhaps make the worm wheel by free hobbing using a suitably sized tap, with the worm itself being made from a bolt with the same thread. No need for dividing head or gear cutters.

21/08/2021 22:46:34

pxl_20210821_212748697.jpg

this shows unit with cover plate off. The worm gear is pinned to a shaft with the knurled knob on the end under the plate. The shaft can slide axially and there's a sprung ball detent down the bearing hole in the cast housing. Fork on the end of the shaft engages with a tongue on the end of the leadscrew. So sliding the knob in and out engages/disengages both the dog clutch and the worm gear. The worm is driven by the pulley groove on its shaft projecting to the right.

pxl_20210821_212820797.jpgpxl_20210821_212852000.jpg

Bit late in the day to measure it and anyway the design is different and I suspect a bit smaller than the C0 version. The belt drive from the mandrel is in my opinion highly unsatisfactory with a short belt with a 90 twist in the loop to accommodate the different axes. To be frank I wouldn't bother with making your own but just arrange a geared DC motor to drive the leadscrew.

21/08/2021 22:12:51

It looks exactly like the Unimat 3 auto feeder though the dimensions may be different. Basically the shiny "knob" with a groove takes the drive O ring that couples to the headstock mandrel. Inside the red box there's a worm that drives a pinion that can engage the end of the leadscrew using a dog clutch operated by pushing/pulling the black knurled knob. I've got one from my Unimat, I'll try to take a photo of the innards.

Thread: cutting spur gears on a mill
21/08/2021 22:08:53

Could we stop calling it a tap when we mean hob? Except of course when talking about trying to use a tap as a hob.

Brian, from this response:

"Pay attention at the back

Or maybe you don't mean herringbone but just have two straight gears with some angular offset to take up the backlash."

...can we assume that indeed you didn't mean herringbone?

21/08/2021 12:56:07

Yes, I know what they are thank you! It's just that though they have the great advantage of being quiet (as a derivative of a helical) and (unlike a helical) not creating a thrust force along the shaft axis, they do not have zero backlash. And making them is difficult. You could I suppose make two helical of opposite hands and mount on the same shaft, but how would you make those with a tap to mate with another similar pair?

Or maybe you don't mean herringbone but just have two straight gears with some angular offset to take up the backlash.

Whatever, I wait with interest to see the results.

21/08/2021 11:21:01

By herringbone, do you mean helical? Why would that eliminate backlash?

Thread: Clinging to the Past
20/08/2021 13:50:09
Posted by Vic on 20/08/2021 12:50:43:

The influence of imperial measurements is still very much evident today. For some youngsters sheet goods must seem to come in weird sizes like 1220 x 2440, until you look at a tape measure. Also look at socket drives - 1/4”, 3/8”, 1/2” etc. I’m sure it must upset the French. You would have thought the EU would have replaced them with metric sizes by now. 😂

They have. 6.35, 9.5, 12.7 mm.

Thread: cutting spur gears on a mill
20/08/2021 13:47:54

Dave (SoD) commented on tooth forms above - as was mentioned earlier the thread form on a tap is in effect a rack and will hob an involute tooth (in an ideal hobbing setup anyway) provided the number of teeth is not too small..

Brian, the basic method has been used a lot for making non-critical worm gears. It will work reasonably well if you gash the blank first to get the right number of teeth, even better if you drive the blank from the cutter arbor with the right ratio like a hobbing machine. Used in a hobbing machine then yes it will work to make gears but the pressure angle will be non-standard and the DP or module, depending on your preference, will be non standard. So only good if you make both gears from the same tap pitch.

What people are trying to work out is whether, if you take the method further to cut a spur gear with parallel teeth, it would also work. If you want to make a gear for a project then usually you need a bit more certainty so would use more of a standard method. I think that's why no one has tried it. Clearly it would be a useful experiment and I urge you to have a go and report back.

19/08/2021 15:40:43
Posted by Andrew Johnston on 19/08/2021 14:44:11:
Posted by brian jones 11 on 19/08/2021 12:05:43:

Seems too good to be true

........

For spur gears it's a useless method. First, the work would need to be swivelled to the helix angle of the tap in order to get straight teeth on the gear. Second, the work would need to be rotated at the appropriate rate, same as when using a hob. Third, the tooth form would be non-standard, and the gear would only work with other gears made by the same tap.

Andrew

For larger tooth counts the tooth form will surely be involute as the tap is in effect a rack form cutter? But indeed the pitches will not mesh with other "standard" gears. A 10 tpi tap as the OP suggested would cut teeth of ~31.15 DP which isn't any kind of standard, and pressure angle 27.5*.

19/08/2021 12:37:57

See **LINK**

Also several threads on this site about variations of the process including what you describe, also known as free hobbing.

Thread: Harrison Remontoire info
19/08/2021 12:01:30

Do you have access to the BHI website?

Thread: Ruggedising a Type 17 Stepper motor electrical connection
19/08/2021 11:45:15

Sugru is excellent for "potting" since you can mould it round the item and it supports itself.

Another method I used on the steppers on my lathe and dividing head, which have flying leads emerging from the motor, is to drill a hole at one end of a small plastic project box, pass the wires through the hole into the box, and glue it down on the side of the motor with Araldite.  Then terminate the flying leads with terminal strip inside the box on to multicore cable run through a grommet, screw on the box lid, and if necessary use a tie wrap round the flying lead for strain relief.  Will post a photo if I can find one.

pxl_20210819_110607213.jpg

This is the X axis drive on my VMB mill.  It uses a Type 23 stepper so a bit bigger, you would need a smaller box.  In this case the 8 flying leads from the motor needed some interconnect to put the windings in series, so they are soldered and heat-shrink sleeved, then the non-commoned ends connected to the choc bloc segments to connect to the leads to the driver - this could have also been soldered to save space.  The leads were actually led in from the end of the box, and protected by moulding Sugru around them.  At the other end the cable I made up has a spiral nylon binding, fixed at the otor end with heat shrink, and again moulded in Sugru.  Box lid has been unscrewed to get this shot.

Edited By John Haine on 19/08/2021 12:00:28

Edited By John Haine on 19/08/2021 12:23:42

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