Eagle Mk3 surface grinder rebuild

  1. Pete.

    Pete. Member

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    Got a good start today hoping to get loads done. Today's job is making new spindle pulleys. The only suitable motor I have is a single phase 1450rpm motor of about 1.5hp so I have to make speed-doubling pulleys.

    Here's the old pulley. It's very rusty and has bits of old belt stuck to it.

    Eagle spindle pulley 1.jpg

    I had to heat it up to get the grub screw out and gave it a little tap around the periphery to see if it would move but no chance, so I had to rig up a puller. I took off the front bearing retainer and luckily it was the same bolt pattern as the rear cover. This meant I could put it on the rear end, fitted backwards so I didn't mess up the mounting face, and use it to pull against. I put a slug of scrap in the end so I didn't ruin the centre drilling for the shaft, in case I ever have to put that between centres sometime. Rigged up some blocks to stop the pulley against the front of the housing cavity and set up a 2-leg puller to push the spindle out through the pulley.

    BTW you'll notice that the grinder head is not cleaned and painted. I wanted to get this work out of the way first and I want to have the bearings out of the head when I hit it with the sander and then paint.

    Eagle spindle pulley 2.jpg

    The pulley was on there VERY tight. Even with heat the puller wouldn't move it so I had to resort to more neanderthal measures. I pulled it up as tight as I dare on the spanner and then hit the edge of the pulley to shock it along a tiny bit at a time.

    Eagle spindle pulley 3.jpg

    About 15 minutes of that and the pulley is off.

    Eagle spindle pulley 4.jpg

    Now it's time to make new pulleys. Vee belts are fast disappearing from motor factors in favour of poly-vee belts so I'm making poly-vee pulleys. Here's the new belt.

    Eagle new belt.jpg

    And this is going to be the new pulley to suit it. The bottom pulley will be twice the diameter.

    Eagle new spindle pulley 1.jpg
     
  2. mtt.tr

    mtt.tr Member

    Messages:
    2,960
    Essex England
    Be aware that the motor has to be pretty small as the knee screw comes bloody low i hastily started mine up dropped the knee through the junction box, as its a motor i had it now hangs out the back
     
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  3. Pete.

    Pete. Member

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    Thanks, I'll go and check that but I think the knee is almost fully down right now with the motor fitted.
     
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  4. awemawson Forum Supporter

    Should have brought that shaft & pulley here Pete. The 60 ton press would have shown it the error of it's ways :clapping:
     
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  5. pressbrake1

    pressbrake1 Forum Supporter

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    2,418
    essex england
    He would have had to bring the whole grinder along!
     
  6. awemawson Forum Supporter

    No just the head assembly
     
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  7. Pete.

    Pete. Member

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    You're right, the screw is actually touching the motor. I'll have to ease the slots open a bit to prevent them from fouling.

    Eagle motor install 1.jpg

    New shaft pulley. I cut the grooves to suit the Micro-v belt using a hand ground 40 degree tool. Damn tip snapped off on the last cut of the last groove.

    Eagle new spindle pulley 2.jpg

    I re-ground the tool and re-cut all the grooves so they are the same. Micro-v belts have 40 degree grooves at 0.140" pitch.

    Eagle new spindle pulley 3.jpg

    Grooves all cut. I could have sunk the grooves in so the top of the belt was flush but I wanted to keep the pulley diameter as big as possible.

    Eagle new spindle pulley 4.jpg

    Then I turned the pulley round and faced the opposite side and turned the boss on the pulley. Only the keyway and grub screw hole left to cut.
     
    • Eagle new spindle pulley 5.jpg
  8. Pete.

    Pete. Member

    Messages:
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    Location:
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    Went down the local tap room with my brother and had a couple hours nap then got on with the pulley.

    Cut the keyway with a hand ground .125" tool. I just engage the spindle lock and keep a hand on the chuck key to keep it lined up.

    Eagle new spindle pulley 6.jpg

    After that I spent a couple of hours washing the old grease out of the bearings and re-greasing them with some very expensive spindle grease from work. Apparently good for 12000rpm in our work machines. After that I re-assembled the whole spindle. I ALMOST dropped a clanger and fitted it up without the belt, that would have been annoying :D

    Anyway I got the spindle installed with the pulley on it and it turns lovely and smooth - the belt is just about perfect length which is a relief since I only wrapped an old bit of argon hose around the pulleys and used a tape measure to get the length. I wanted 2300mm, the closest belt they had was 2315mm and it just fits at the end of the adjustment. The bigger pulley I have to make will help.

    I hooked the belt over the motor vee pulley temporarily and measured the spindle speed so I could calculate the diameter I need for the new micro-v pulley.

    Eagle pulley ratio 1.jpg

    Then I ran the machne for the first time since getting it. Tacho says I'm getting 2300rpm

    Eagle pulley ratio 2.jpg

    Ideally I want around 2900 rpm for my spindle speed to run my 8" wheels at about 6000sfpm. My motor is 1450rpm and the bottom pulley is 115mm giving me 2300rpm. I need to increase the pulley size to 145mm to get my 2900 spindle speed, so that's my task for tomorrow.
     
  9. Welderpaul

    Welderpaul Moderator Staff Member

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    Project threads are few and far between these days, thanks for posting Pete, an enjoyable read and you certainly know your stuff:thumbup:
     
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  10. Pete.

    Pete. Member

    Messages:
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    A little update to this thread. It turned out that the spindle bearings were shot. They are a pair of angular contact bearings 1" bore 2.5" OD and 3/4" wide. When I made a test grind I could hear them rattling and my test piece had a fish-scale appearance all over it where the wheel was bouncing about during cutting. I did some experimenting by putting 5 thou shims in between the bearing outer races and that did improve the finish a lot but still it was fish-scaling a but plus the bearings ran warm and were still noisy.

    By some providence Ali was giving away some bearings in the freebies section which looked to be about the right size so I begged them off him. Turned out they were the EXACT size I needed but alas not angular contact, which meant they were no good for the front pair but were perfect replacements for the original standard bearing at the rear of the spindle, so thanks @Ali :thumbup:.

    Anyway, I decided to bite the bullet and use modern bearings as they were 1, cheap and 2, plentiful if they ever needed changing. So a pair of NSK 7206 bearings were procured that meant I had to make adapter sleeves for them.

    Here is the sleeve to make the 62mm bearing fit in the 2.5" housing. It was all turned and bored in one setup and the wall thickness is just 0.75mm. It's made as a light press fit in the housing and a sliding fit for the bearings. The bearing sits proud by 0.5mm so that the two bearings are clamped together tight by the front cap.

    Eagle new bearing sleeve.jpg

    After that I made another sleeve for the 1" diameter spindle with a press fit 30mm sliding fit OD for the bearings (no picture of that I'm afraid). Both sleeves have a 6.1mm lip on the back side to make up the thickness difference between the new 16mm and old 3/4" wide bearings.

    I put it all together and did a test grind. The back half is the new grind test and the front half was with the old (shimmed out) bearings. The first test was much worse than both.

    eagle new bearings test.jpg

    So that's a vast improvement and now I can comfortably finish the last bit of assembly and painting. I'll make a table guard and fit a new work lamp, The only other thing I will consider is cwapping the single phase motor for a 3-phase. I reckon that will improve the finish even more.
     
  11. scottmk1

    scottmk1 Forum Supporter

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    Location:
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    Good work Pete. Regarding the new bearings, was it still possible to get the correct size version if wished to go that route?
     
  12. Pete.

    Pete. Member

    Messages:
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    I had several places which were advertising the correct size angular contacts as NOS, but none returned my emails. After doing a bit more research I found that they were a common size for British Leyland (I think) wheel bearings from the '70's and the ones on offer were those type.

    I figured that even mediocre modern bearings would be as good as spindle bearings from 50yrs ago so I bought some new NSK angular contacts with standard c3 clearance.
     
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  13. Pete.

    Pete. Member

    Messages:
    9,340
    Location:
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    Making a guard for the grinder today. This one is a 'W' model for wet grinding which originally came with a nic cast ally guard but the guard was not with it when I got it. I brought home some ally angle pieces salvaged from site. They were trim support brackets for double glazing in a large building. More use to me than just throwing them in the scrap.

    Marked out the end pieces and cut out for welding. It's just a guard so no need for super-accuracy.

    Eagle guard 1.jpg

    Eagle guard 2.jpg

    Set up for welding the corners.

    Eagle guard 3.jpg

    I needed to fix the ends down in order to make the middle section, which has to be lower and wider to give access to the mag chuck handle. So I drilled the first hole and made a transfer pin to mark the adjacent ones.

    transfer pin 1.jpg

    transfer pin 2.jpg

    Transfer pin gets the mark spot on for drilling

    transfer pin 3.jpg

    I fixed the ends down and made a section for the middle. Tacked it up in place on the machine.

    Eagle guard 4.jpg
     
  14. mtt.tr

    mtt.tr Member

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    2,960
    Essex England
    Thats my next job for mine, smart job pete
     
  15. pressbrake1

    pressbrake1 Forum Supporter

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    essex england
    I’d say ordinary bearings are good enough for your application but to say high grade spindle bearings from 50 years ago (1970)are equivalent to average modern bearings is nonsense
     
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  16. Pete.

    Pete. Member

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    If I'd said that it would be nonsense. I don't think they are anything more than 'ordinary' grade TBH. The last spindle bearings I had cause to remove were covered in a myriad of annotations etched on different faces. These have nothing more than a bearing number.

    I wouldn't call the Eagle anything more than basic TBH.
     
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  17. Pete.

    Pete. Member

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    Location:
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    The bottom part of the guard is finished and ready for paint. The end guard is going to be a separate piece that bolts on.

    Eagle guard 5.jpg

    Hopefully I can get the head stripped down in the next hour and a half and that ready for painting too.
     
  18. Parm

    Parm Temporarily operating from the Devon Annex

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    @Pete. Thats going to be better than new by the time you’ve finished with it
     
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  19. Pete.

    Pete. Member

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    Nice of you to say that Parm but I'll make do with 'as good as I can get it'

    Anyway, the spindle has a hole in it which I assume must be for a spindle lock pin but I see no facility for a pin so I've knocked up a quick spindle lock and drilled the top plate for it.

    Here's the spindle lock, it's just a couple of pieces of ally and a cut down 8mm bolt and a spring inside.

    Eagle spindle lock 1.jpg

    And here it is installed. now all you have to do is press the plunger and turn the wheel so that the hole lines up, then you can put a spanner on the front nut and remove the wheel.

    Eagle spindle lock 2.jpg
     
  20. Pete.

    Pete. Member

    Messages:
    9,340
    Location:
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    Yesterday after a bit of a family bar-b-q I got stuck into re-fitting the electrics. Not much to it just a lead with a plug into the motor switch and down to the motor. I had forgotten to paint the wiring conduit so that's a job for another day but here it is installed. Whilst I was about it I made a mounting plate for my de-magnetiser, I mean what better place to keep it than on top of the machine that requires it's use? Didn't get around to taking pictures yesterday so I took some this evening.

    Eagle switch demag.jpg

    Also found a nice sheet of steel at work today to make a new back cover for the base. And some 2.5mm flex for a power lead. Also needs painting some time later.

    Eagle back plate.jpg

    And finally some pics of a few test grinds. I'm a grinding novice but I'm quite pleased with how they have come out. I didn't buy super-expensive precision bearings for the spindle just a triplet of matched angular contact bearings. The originals had none of the markings you normally see on old super-precision bearings, just a stampled bearing number so I doubt they were anything more than standard jobs. Also there's no facility for balancing the wheels like on other grinders so all I could do was dress the wheel with a diamond.

    Still, the results are satisfactory enough...

    Eagle test grind 1.jpg

    Eagle test grind 2.jpg

    Eagle test grind 3.jpg
     
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