A Hendey 9 T&G "wreck" - Page 3
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  1. #41
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    You are correct. I somehow mixed SR with 1T. I am working on something to blame it on- neutrino burst, maybe? More likely encroaching Alzheimer's. I can't read the parts list on my laptop, which is all I have working right now. My main computer has video thrombosis. Likewise, I cannot see another wire on the CT unless I go to the full sized picture. It does seem to be there, though. You would expect a fourth, but there is no reason that a CT cannot be used with a common lead, sort of like an autotransformer, although I have never seen one like that. I would really like to see a schematic for the three phase unit.

    Re mag amps in general, look up "reset magnetic amplifier". I inherited a 4th axis that would go right on my Boston Digital CNC mill, but it turns out to be a special made for Tree mills and even the people who made it don't know how to run it because it used a Tree proprietary controller. It uses a Baldor permanent magnet field DC servo motor that I have past experience with. A reset mag amp would be perfect for it. The usual mag amps are limited in response because of control winding inductance. The reset ones can go from off to full current in a cycle. The bugaboo with things like 4th axes is needing full torque at a very low speed. In that condition an analog transistor driver is very difficult because almost all the supply voltage is dropped across the transistors. The dotted line on the dissipation graph is the killer. Analog circuits sometimes have SCR pre regulators, which adds another layer of complexity. Switchers avoid that, but I don't like to work with them. In mag amps, all that copper provides a thermal mass that allows huge surges without damage as long as the surge doesn't last too long.

    Bill
    Last edited by 9100; 01-17-2011 at 07:54 AM.

  2. #42
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    Pete has been trying to find a wiring diagram for his 3-phase controller. (I think Hendyman is looking for one for him.) So far the single-phase diagram is the closest that has been found. He's got a problem with speeds above base speed, so if all else fails we may need to try to create a diagram from the wire numbers, etc. What fun...

    Cal

  3. #43
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    Default The Scraping Starts

    Well, I'm finally home for a few days and I got a start made on the bed.
    I spent the afternoon and evening scraping the one of the tailstock ways.
    MAN THAT BED IS HARD! The drawing shows it as 65-70scleroscope ( somewhere around 50-53 rockwell c)

    As you can see from the pictures I have gotten about 1/2 of 1 surface done (kinda) The surface was worn about .0025, and I would think that i got about half of that gone.

    Using the biax, and both sandvik and dapra blades, I can get about 6 sqin scraped before I can feel the blade getting dull.
    I am going to check some of the reference material and see if different blade geometry might help.

    If I don't get more progress tomorrow, I'll have to start saving some coins for the grinders...

    More to follow

    Pete


  4. #44
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    I found that 4* negative angle worked the best. You're about right on the life of the edge, that's why I have/had 5 or 6 blades ready for use. Once they all were dull, off to the grinder. Usually one pass on each edge did the trick. I've done 3 beds, and probably completely used up 3 blades, still got 6, or so.
    Harry

  5. #45
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    Thanks Harry!
    I tried the -4* blades today and had much better results.
    I have just about got the tailstock way upper flats to carry all the way. i have about .0005 left in one area. It sure takes a lot of scraping cycles to get that much off though!

    I'll post a few pictures tomorrow.

    Pete

  6. #46
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    Default A change in Tactics

    After much consideration, and 2 day of recovery from last weekends round of scraping I have come to the decision that I am going to send the bed out for grinding.
    With the limited time I have available, I will probably be 100 before I get it done, so I am going to focus on the things I am good at (ie. mechanical repair) and get the bed ground.

    One of the issue I wrestled with is cost.
    Grinding is going to cost approximately $2000, which is not an inconsequential amount of money, but when one figures out the cost of tools, materials and heating ( I live in the "great White North") it begins to seem a bit of a wash. The value of the finished lathe will probably justify the expense.(or so I like to tell myself)
    I hope to get the bed to the grinder's shop by the end of March.

    SO... it's back to working on the drive, and start working on the major components.

    Pete

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    I sent my 10ee bed to Commerse in Dallas for $1,000 including shipping. I live in Ohio so you might want to check into shipping the bed out for regrind.

  8. #48
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    Pete,

    Your countryman, PM member and 10EE owner collector has two bed grinders that he has restored:
    Junk Yard Find

    He's located in B.C. Give him a shout, maybe he'll make you a deal on the grinding job?

    Cal

  9. #49
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    Default More drive stuff

    I was out in my shop this evening and I spent a little time on the Hendey.
    I looked over the wiring and that is a good new/bad news sort of thing. Many of the wire markings are visible, and seem in good shape (good) but a great many of them are either unmarked, or the markings are so dirty/burnt as to be unreadable. The wiring is also very hard and I don't think that it will like much poking and prodding ( bad).

    I also was curious about the armature and field voltages, so I got out my meter and made a few measurements.
    The wires in the front terminal strip marked a1, a2, s1,s2 and f1, f2 go directly to the motor from the terminals so I made my measurements there.
    With motor in low speed a1-a2 voltage is close to 0 vdc and varies with the rheostat movement to a maximum of 210 vdc
    With motor in low speed f1-f2 voltage is about 97 vdc. as the rheostat moves toward high speed voltage starts to drop and get to 53 vdc where it stays ( more or less)
    I had a look at the rheostats and saw that the "F" rheostat has some damage about 25% from one end. So I started up the drive again and noted where the "f" voltage hung, and sure enough it is at that spot on the rheostat (the wiper also sparks as it crosses that spot)

    SO... I think that I may have found at least part of my problem.
    The rheostat is am ohmite and I have a partial p/n ( 40459) which I will contact them with and see if I can at least get some idea what it is. I also have some possibility that one of the other owners might be able to find the p/n on their machine.

    Have you ever heard of anyone repairing those rheostats?

    Pete


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    That looks like a standard Ohmite pot. It should have the resistance marked somewhere. I am at home and all the similar ones I have are at the shop, but will look tomorrow for the location. If it is open at the bad spot, you can disconnect it from outside influences, rotate the wiper to just brfore the bad spot and measure the resistance, then figure the proportion for the full travel or measure the resistance of each part and add them. There will be a slight loss from the bad area, but it probably is a standard value. You might be able to scrape the glaze off the wires on the OD and solder a jumper across the open spot, but it probaqbly is not worth the effort since you likely can get a replacement from an electronics supplier.

  11. #51
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    Default Hendey T&G power supply

    Back at work on the 9" T&G.
    I've taken the motor and power supply out of the base to clean and paint the compartments.
    I have taken the time to document the connections and have repaired some obvious minor deficiencies.
    Here are a couple of pictures of the main power supply. It is a 2 person lift, it must weigh in at 100+ lbs.


    One of the things I have discovered is that one of the coils on the small magnetic amplifier (black transformer like contraption in the first pic upper r/h) appears to have a bad winding. The resistance is very different from any of the other windings. This Mag Amp controls the field voltage, and this may be the reason the motor won't go above the base speed.

    Anyone know a place to get this sort of unit repaired or rebuilt?

    Cheers
    Pete

  12. #52
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    Default Back to the non-sparky stuff...

    Part of the sequence of jobs to be done on my refurb is to remove the contents of the base casting to clean and paint the interior. This brightens it up and allows easier cleaning in the future.

    So with the power supply and motor out, I also removed the back gear drive gearbox. (switches the power from the back gears to the main spindle)

    Well... although it functioned ok the disassembly for cleaning revealed something completely different. All the bearings (6) are trashed, and the input and output shaft keyways are badly worn out as are the keyways in the pulleys.
    These shafts are not going to be easy to just remake as the have hardened splines on the other end.
    Anyone care to make a suggestion as to an appropriate repair?




    Pete
    Last edited by shapeaholic; 03-31-2011 at 08:59 PM. Reason: Updated picture

  13. #53
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    Quote Originally Posted by shapeaholic View Post
    Anyone care to make a suggestion as to an appropriate repair?
    The shafts might be able to have a new keyway cut on the other side and have the bashed up side simply cleaned up, maybe something similar for the inside keyways. My preference would be to weld up the shafts and bush out the others and cut new on both, it seems to work out a lot better for me.

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    Pete,
    I prefer to weld the shaft up, re-machine and cut a new keyway opposite the weld. Yes I know you will be threading an interrupted cut thru a weld to pick up the orig. threads..

    For pulleys I have cut the center out .5" or larger oversize made a plug and pressed it in with loctite. Then tapped 2 or 3 holes for setscrews at the junction of the parts to make a threaded keyway and key. Then loctited the setscrews in or riveted over a pc of all thread rod with loctite there too. Bore and key the bushing after the loctite has set, it will compress the bushing with .5" walls when it sets!

    I have done this on the input shaft of Clausing & Harrison lathes and the highspeed shaft on a 5" Lucas plus countless smaller projects.

    Bill
    Last edited by hitandmiss; 03-31-2011 at 07:02 PM. Reason: typos

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    Russ and Bill,
    I have the shafts ready to go to the welding shop tomorrow morning. My welding skills are not up to this sort of work :-))
    I am going to get the threaded ends welded all around, and I'll recut the thread. One of the shafts is worn there too.
    I have some material to make bushings for the pulleys. My only concern is that I don't have a lot of material to bore on the pulleys. I would like to have at least .125" above the keyway.

    Hopefully I'll get some of this done over the weekend.

    Pete

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    Quote Originally Posted by shapeaholic View Post
    Russ and Bill,
    I have the shafts ready to go to the welding shop tomorrow morning. My welding skills are not up to this sort of work :-))
    I am going to get the threaded ends welded all around, and I'll recut the thread. One of the shafts is worn there too.
    I think you want to turn the thread off and a little under before they weld it back up. If you don't there's a fair chance that the threading will peel the weld out. If they have an induction heater you might consider getting the end normalized after the welding is done.

    I have some material to make bushings for the pulleys. My only concern is that I don't have a lot of material to bore on the pulleys. I would like to have at least .125" above the keyway.
    You can get away with a little less if you're happy gluing the bushing back in with bearing retainer. I think that it works better for non-shock loads than a shrink fit or press fit, and there's no stress on the bushing or sheave. You can kind of mix the techniques by lightly knurling the outside of the bushing after cutting the sheave a thou over - at least that's what I tell folks when the bush rattles a bit in fit before knurling. (Besides, you want it to center on the sheave but have room for the retainer - .002" gap for Loctite 640(? - the green bearing retainer) and that means knurling or peening with a automatic center punch)

  17. #57
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    Quote Originally Posted by shapeaholic View Post
    Back at work on the 9" T&G.
    I've taken the motor and power supply out of the base to clean and paint the compartments.
    I have taken the time to document the connections and have repaired some obvious minor deficiencies.
    Here are a couple of pictures of the main power supply. It is a 2 person lift, it must weigh in at 100+ lbs.


    One of the things I have discovered is that one of the coils on the small magnetic amplifier (black transformer like contraption in the first pic upper r/h) appears to have a bad winding. The resistance is very different from any of the other windings. This Mag Amp controls the field voltage, and this may be the reason the motor won't go above the base speed.

    Anyone know a place to get this sort of unit repaired or rebuilt?

    Cheers
    Pete
    I do that for a business. I also design and build transformers and mag amps from scratch. See my website
    Home Page
    I have the winding equipment, a large stock of different wire sizes and vacuum impregnating chambers. I also need work, so I would like to see your mag amp.

    Bill

    Edit: The odd winding may be the control winding. You would expect two low resistance ones and one much higher. Obviously you would want to check it before paying shipping charges on something that heavy.

  18. #58
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    9100 Bill,
    Could you please post some advise as to how I can go about checking the MagAmp?
    If I could do some checks to confirm it's serviceability (or not) I could then spend time looking elsewhere for "problems"

    Thanks

    Pete

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    A basic saturable reactor consists of a winding with enough inductance to block the AC voltage to whatever minimum current the designer deems acceptable. There will always be some. The core is sized to just stay out of saturation at the end of an AC half cycle. This is just about the same as a typical transformer primary winding and I have used transformers with the other windings removed for the basis of one. Then you add a control winding that is fed a variable DC current which makes the core reach saturation at the end of the half cycle. The more DC, the sooner it gets there and the greater the AC current flow. However, this configuration is not very usable because of the AC voltage induced in the control winding. A practical reactor is made by combining two of these units with the AC flowing in opposite directions and the control winding common to both. The AC voltage induced in the control winding cancels, allowing as many turns as desired on it without AC voltage fed back to the DC circuit.

    From there on, things can get complicated because some circuits have feedback windings using some of the output rectified and applied to the extra winding for more gain.

    You want to look for two low resistance windings on separate legs with the AC input connected one wire to each winding. The output will be from the other ends of these windings. Then there should be a higher resistance winding or one on each leg connected together so that the AC induced by the power windings cancels between them. To test, you would connect the AC the same as in the unit, a load on the output, an incandescent bulb or two works well, and a variable DC voltage to the high resistance winding. You should be able to vary the bulbs through their brightness range.

    Naturally, it is well to look at the circuit as installed first to get as good an idea as possible how it is used.

    Bill

  20. #60
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    Bill,

    I've been working with Pete off-line. He's figured out the wire numbers for most of the components and I'm in the process of working out a schematic.

    The small mag amp has a pair of saturable reactors, each with 3 windings. One winding on each connects to the small rectifier above the 6 big saturable reactors, providing the field current; the other two are control and bias windings. The bias winding is the one with the high resistance. The two bias windings are connected in series with a 10k resistor to a simple DC power supply module on the front panel.

    I'm pretty sure that Pete's problem is with the field control power supply. It has a 330 VAC input connected to a bridge rectifier. The output of the bridge is reading 730 VAC, 0 DC. I suspect that one of the diodes is blown or there is a bad connection and the remaining diodes are interacting with the inductance of the mag amp and acting sort of like a buck-boost converter.

    Cal


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