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  1. J

    American Rotary DIY panels. A.R. says need delta wound motor...?

    I couldn't figure this out for a while so I worked the numbers out a handful of years ago. There is no difference between delta and y... Except with regard to heat distribution. Most motors are concentric windings, machine inserted, not lap or mush windings (which require a lot of work by hand...
  2. J

    Seeking knowledge on Southbend Lathe Spindle Bearing/Sleeve Bearing/Expansion Bearing.

    Seems to me you can peen the material back down, on the bearing, file the bearing and expander as needed, and glue or solder a shim to the side of the expander. Alternatively you can file the bearing back to a good l dovetail, solder a shim to it, then re install after cleaning up the expander...
  3. J

    3450 vs 1760 RPM for rotary phase converter

    Warning: old tread from 2009. I read all of it, will echo some earlier points: for a given hp, the higher efficiency, higher power factor motor will be better. Rpm is irrelevant, except that due to geometry constraints, 1200 and 900rpm motors are generally 10 points lower on power factor...
  4. J

    lost a couple of parts to a 9a

    Saddle lock... Consider moving it to the left hand side of the apron, especially if you are not going to rescrape the apron and grind the ways. It's just a plate with three raised areas for contact. There is room you could build a different kind of lock, actuated by something sticking out of the...
  5. J

    is there any gain to switch an from single phase air comp motor to 3 phase with a VFD to draw less amps

    Friend of mine uses Schwartz oil less compressors and has in general found them to be fairly reliable with the exception of the connecting rods fatiguing, I have repaired them several times, and found some interesting failures particularly with the crap we bought on ebay that were "rebuilt" by...
  6. J

    Pickup hitch mounted hoists/engine lifts

    I made one, it needs a bunch of improvement. It works but it's heavy, and too much backlash. Basically I built it all from scrap 2.5" angle iron welded into a square box beams. So a 5 foot long beam fits into the hitch at a 90 degree angle, with a 4" pipe a foot long welded vertically sticking...
  7. J

    Electronic gearing for gear hobber

    with regard to the cnc gear hobber i want to make.. rather than take an 8 radial segmented hob and make the gear supposedly more accurate by slowing the feed rate a lot.. instead you can run it at an average speed, finish the gear, return to zero, slide the hob one 1/16th of a tooth (1/8/16th of...
  8. J

    Electronic gearing for gear hobber

    You can call it what you want but in terms of number of facets or scallops that the gear tooth is going to be cut by, a single point cutter will replace a hob provided you take 8 to 16 times as many passes, it has no relation to the number of teeth other than the fact that fewer teeth is less...
  9. J

    Electronic gearing for gear hobber

    On a mechanical machine sure. Electronically it's easy. Add distance x to the hob's path along it's axial rotation axis, rotate it backwards or forwards to compensate for the extra rotation, otherwise you turn the gear into a helix of a completely wrong tooth shape. For a given spur gear...
  10. J

    Braking resistor on derated VFD

    A 480v vfd will see around 750 volts on the DC bus before it sends current though the brake resistor. It is no surprise to me that a 10hp drive recommends a nominal 50 ohms resistor, that corresponds to 15 amps of current or 11000 watts of power. Basically, what that means is the drive is...
  11. J

    Electronic gearing for gear hobber

    Seems to me that is rather easy. Here is an example: Gear rotates 500 times, hob spins 4999 times, hob travels x distance across the gear face. For a spur gear the hob would rotate 5000 times for a 10 tooth gear. Helix angle is set by the ratio of the distance x of the gear to the pitch of...
  12. J

    Electronic gearing for gear hobber

    So they make servos that can take step direction, let's assume for the moment that they are as stiff as a stepper of equal power rating. Suppose you have a 1 or 2kw servo driving the hob through a 10:1 gear reduction. Keep in mind that the stepper with micro stepping is good but at it's limit...
  13. J

    550 pound anvil origin question.

    What I mean by grain is that wrought iron has a grain that you can see, and a lot of slag... But so does the top plate. It doesn't grind to a polish the same way steel does, and certainly not polished like the stainless steel weld rod my grandpa wrote on the top plate with. So I'm really just...
  14. J

    Cracked cylinder head. Stitching pins and new seats

    Has anyone tried to braze one of these heads with 56% or 45% silver rod? I'm guessing it won't hold due to the tensile forces involved.
  15. J

    Spindle seizure ......Stoning the high spots.....SB9

    There are lots of ways to do this. The tail end of the spindle looks like something funky was going on there. It looks ok but if I had to guess I might say the tail end seized up, as it looks strangely polished. Not the chuck end. Chuck end... all that scoring didn't happen at once. What I...
  16. J

    Motor re-wire to reduce hp

    Get a 480v vfd, run it from a transformer, and program the vfd for around 300 volts at 60hz. This will give you around half the hp at less than half the no load amps. ( All of which get recycled in the vfd anyways, which only has to supply the motor losses and the load) Keep the motor in...
  17. J

    Hot rolled pickled & oiled sheet - what paint system works?

    When I was researching the adhesion of epoxy to steel, I found some sources which explained that the limit is 1500 psi and the epoxy is adhering to the oxygen atoms bonded to the steel.. not the iron atoms. The steel treatment they recommended was basically wipe it clean of oils, then 10% hcl...
  18. J

    Where would you buy a welding helmet today?

    The damage to your eye is thermal, however I will add that a friend of mine bought a cheapish helmet and the time delay messed up his eyes somehow before he figured out what was going on. (Primarily Tig). It's not a thermal burn to the retina but a neurological effect in either his mind or the...
  19. J

    Line Voltage too High

    High line voltage let's them drop it when they need to, to reduce the load. Good part of the grid is still resistive heat. Motors only use less power at high line voltage if they are loaded over 75% nominal load. I am curious what the average load is. At one point in various areas especially...
  20. J

    VFD and 3ph AC Motor - Nameplate shows PWM and CSI ratings?

    No, the motor would burn up. You have to add some volts to a linear volts per hz line in order to get the magnetic flux density needed to produce a torque. (This is mostly because of the winding resistance) Better than average vfd manuals explain all of this and will give you examples of how to...
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