Eagle Surface Grinder Build

  1. Pete.

    Pete. Member

    Messages:
    9,202
    Location:
    Kent, UK
    They must have had problems with this at the factory too because I just stripped the table from mine and the rack has slots cut in the bottom so it can be adjusted on stand-offs.

    eagle table rack.jpg
     
  2. RobCox

    RobCox Member

    Messages:
    109
    Location:
    Cambridge, UK
    I've finally got a new rack on the bottom of the table! I approached cutting the rack a bit more scientifically this time, starting with measuring the spacing from the rack mounting surface under the table to the centre line of the hole where the new table feed spindle will run. I started by turning a rod down to the diameter which fits snugly in the bore in the saddle, cut a point on the end then milled half of it away to give me a flat surface at the centre of the spinde that I could measure with a depth mic:

    20191130_145001.jpg
    20191130_150304.jpg

    View from below whilst the measurement is being taken:

    20191130_145023.jpg

    I checked the heights of the 123 blocks and parallels against a set of gauge blocks. This measurement gave me the distance from the spindle centreline to the ways. I then measured the table:

    20191130_151354.jpg

    I changed my mind about the MOD / DP of the gear rack I was going to cut. I took a MOD 2, 14.5 deg PA rack and gear off but due to the availability of cutters I've gone to DP 12 now, so used that for the calculations on the thickness of the rack.

    I tweaked the width of the cutter teeth on the TC grinder and used this shop-ground tool to cut the rack. I've bought a suitable cutter to do the helical pinion now.

    Same recipe as before. One pass per tooth with a 3/32 slitting saw, not to full depth but just to remove some of the material to save wear on the rack cutter, then one further pass with the bevelled tool to full depth to form the teeth. This time I used some 1 1/8" hot rolled, milled down to 1" square, for the rack. The final rack was as straight as the mill cut it - that's to say the table sags a few thou at the extremes of travel and required drawfiling to improve it.

    20191202_141646.jpg

    And finally the rack assembled on the bottom of the table:

    20191203_181829.jpg

    Rob
     
  3. Pete.

    Pete. Member

    Messages:
    9,202
    Location:
    Kent, UK
    Superb work again Rob. Does your rack not sit up on spacers like mine? Can't see the marks.

    PS if you want to borrow my flaker to oil-flake the underside of the table let me know. The better the oil retention the longer the machine will last.
     
  4. RobCox

    RobCox Member

    Messages:
    109
    Location:
    Cambridge, UK
    No spacers on mine. The rack that came off sat flat on the machined surface under the table. I've made the rack the correct thickness to engage on the helical gear with a generous clearance to allow for wear. I don't think that the rack I removed was the original, but I have no drawings or exploded views to go off so I'm making it up as I go along, and where something is present and worn out I'm replacing like for like where I can.

    Thanks for the offer of the flaker but I'll pass on that for now thanks. My scraping hasn't generated more than about 15 points/in so there will be plenty of gaps for oil retention. Plus I've no experience of power scraping/flaking and I'd hate to ruin what I've achieved so far. I doubt I'll wear it out. Having said that, I've a few jobs that it might be handy for if it were up and running!
     
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  5. Ancient_Axeman Member

    Messages:
    24
    Location:
    Hastings, UK
    Hello Rob
    I just joined with questions regarding my Old Capco surface grinder and was amazed to see the quality of your restoration project!!
    Very well done Sir and keep up the good work! its so nice to see people ressurecting these old machines. Okay i will admit that i am slowly getting addicted to buying old machines to do up to give myself a good compliment of tools!
    I am aiming to restore mine so I can regrind my woodchipper blades for work among other things!
     
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  6. RobCox

    RobCox Member

    Messages:
    109
    Location:
    Cambridge, UK
    Thanks for the compliments @Ancient_Axeman. For the next week and a half Christmas social commitments and work will keep me out of the workshop, but I'm hoping to make some decent progress in the 2 weeks I've got off over Christmas.

    As for getting addicted to buying old machines, you'll no doubt have seen that I've already acquired my next project for when I finish this one!
     
  7. spencer 427

    spencer 427 Member

    Messages:
    6,833
    Location:
    uk colchester
    Very nice work.
     
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  8. RobCox

    RobCox Member

    Messages:
    109
    Location:
    Cambridge, UK
    Its been nearly a month since I posted any progress on this rebuild. That'll be becausewhat with Christmas socializing, work and illness, there hasn't been much direct progress!. I've spent the workshop time I've had getting set up to cut a new helical gear to drive the table.

    I've had the universal dividing head for a while, had it to bits and cleaned it up... 20191104_171454.jpg

    In order to be able to use this to cut the gear, I've had to make a long list of bits: keys for the base to make aligning it easier, a riser block for the footstock from my spindexer (since the div head didn't come with one), various spacers and a locknut to secure the gears on, and an arbor/spacers/locknut to hold the gear blank:

    20191223_155237.jpg

    I cut keyways in the arbor as the gear will be keyed on to the table drive shaft (when I get round to making that). Didn't have any 3/16 keystock, but had some 6mm. Could have done with a surface grinder to finish it to size... hang on, lets try to tool & cutter grinder with the mag chuck that came with this SG:

    20191231_093510.jpg

    Worked a treat! Not much range of Y movement available though, but enough for a key.

    Next problem was the gears to drive the dividing head to produce the correct lead on the helical gear. Lots of spreadsheet calculations led me to require a ratio of 9/8. This will cut a helix angle of 30.03 degrees, close enough given that trig functions are involved in working it out, so there's no nice rational numbers here. I don't have a full set of drive gears for the Div head, the 44 to 64 gears are missing. The other problem was that the drive gears have a 3/4" bore but the table spindle on the mill is 5/8". To sleeve that, with a key, and maintain concentricity so the gears don't bind seemed awkward to me, so I used the arbor I'd made together with the div head to cut a couple of gears to give me options (just like with screwcutting gears on a lathe, there's some combinations that just won't fit). I cut a 45 to fit the table spindle, with an idler to space things out, driving a 40T gear to give me the ratio. Here's the gear about to have it's teeth cut:

    20200103_162208.jpg

    The gear was made in two parts. The long sleeve picks up the keyway on the table spindle and the gear sits at the right point to pick up the dividing head gears. As this was the first time for me using the div head, I went round with the erasable cutter (sharpie) shown in the picture first as there was a fair amout of time invested in this blank and I didn't want to screw it up.

    Gear cut and fitted to the drive train (bit blurred, but shows the idea):



    20200104_114746.jpg

    To check my calculations were good, I put the original mod2 gear on the arbor and checked with the sharpie that the lead it was producing was correct:

    20200104_114740.jpg

    So time to try it for real. As I write I haven't cut a steel gear yet, but I've done a run with a delrin blank:

    20200105_121150.jpg

    More blurred photos. At least the swarf gave the workshop a seasonal look! Actually it didn't go so straightforward - after the first cut at 1/2 depth, the mill table power feed packed up. Turns out that a spring pin had dropped out of the lever that engages the dog clutch. I had to take the table off, fix it then set everything up again. The second time I went for full depth cuts, having lined up the one slot I'd cut as near as poss. This is the end result:

    20200105_123050.jpg

    It seems to fit the rack teeth, holding it in about the right place:

    20200105_122913.jpg

    Now to cut the gear in EN8 for real...

    Rob
     
  9. RobCox

    RobCox Member

    Messages:
    109
    Location:
    Cambridge, UK
    I finally got round to cutting the gear in EN8. Turned out OK and I learned a few things along the way.

    First couple of pics are the technique I used to work out the height to set the cutter. I used the drive centre and the footstock centre points to eyeball the centre of each side of the cutter before using the 1/2 function on the DRO to centre it:

    20200106_082355.jpg 20200106_082524.jpg

    That was about as good as I could get it. For anyone concerned about the lack of precision, this cutter is made of the finest Chinesium and weeble-wobbles visibly, but I didn't fancy spending more on a cutter than I paid for the grinder and I doubt I or anyone else will notice once it's running. The arbor that I used was one that came with my TC grinder. It originally had a morse 2 taper on the end, which had been abused to the point where the only good thing I could do with it was turn it down to a 16mm parallel shank to hold in a collet. There's probably a bit of runout there too.

    There are no flats on the arbor to get a good grip on it while the securing nut is tightened. Neither the arbor nor the spacers have a keyway so the cutter is driven by friction alone and yes, due to the vibration and the characteristic intermittent cutting that almost every horizontal cutter I've used seems to exhibit, the nut cam loose during one of the cuts. Minor excitement whilst the feed tried to drive the stationary cutter through the slot, but I was watching it like a hawk anyway and caught it before any damage was done. The arbor will be getting some flats before it gets used for milling again!

    The tooth depth worked out as 0.180" (2.157/12DP), and I split this into 3 cuts as the mill isn't the most rigid, especially driven from the vertical head like this. 90 thou deep on the first pass, 60 for the second due to the increased cutter engagement and a 30 thou finishing pass, all at about 150rpm (200rpm belt settings and some frequency reduction on the VFD). About 1 1/2 hours of concentration. Here's the final cut, showing how little room for manoeuvre there is with this setup:

    20200106_101405.jpg

    And here's the finished item next to the delrin one:

    20200106_102534.jpg

    Rob
     
  10. mtt.tr

    mtt.tr Member

    Messages:
    2,815
    Essex England
    Nice bit of work
     
  11. Pete.

    Pete. Member

    Messages:
    9,202
    Location:
    Kent, UK
    That's nice Rob. I love the simple yet effective method of centring.

    That's a nice drive dog. Is it home made?
     
  12. jordhandson Member

    Messages:
    737
    Location:
    Dorset
    Good post Rob thanks.
     
  13. Milkybars

    Milkybars Forum Supporter

    Messages:
    329
    Location:
    Essex
    Rob, slight thread diversion ..could you photograph how you have done the DRO on the Elliott (Z &Y). I have done Third of mine (X) and keep going back and looking at it (basically avoiding it).
     
  14. RobCox

    RobCox Member

    Messages:
    109
    Location:
    Cambridge, UK
    @pete, yes, the drive dog is home made. Lots of manual milling (drawfiling) to get it looking pretty. Takes up to about 3/4" shaft.

    @Milkybars, I'll take a few pictures of what I did and post them here. My DRO uses magnetic scales. I originally installed it on a Sieg SX2 that I started with. The slimline scales fitted on that machine very nicely. When I traded up to the Elliott I bought new magnetic scales (the cheap bit) and re-used the read heads (the pricey bit). Once the Elliott was up and running, the Sieg got sold as it occupied valuable workshop space. Funny, I quite happily sold the Sieg mill, but somehow I can't seem to bring myself to getting rid of my Sieg SC2 lathe, even though I never use it now I've got the M300. Backup plan just in case I suppose. Lots of bits of the M300 got re-made on that little Sieg.
     
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  15. Milkybars

    Milkybars Forum Supporter

    Messages:
    329
    Location:
    Essex
    Cheers Rob, it seems we both own the same mill and lathe :)
     
  16. RobCox

    RobCox Member

    Messages:
    109
    Location:
    Cambridge, UK
    About time I did another update. I've tackled the table feed spindle. Without diagrams or pictures of the original parts and having to correct the wear on the casting, I'm making it up as I go along. As I'll explain below, I don't get it right first time.

    First job was to sort out the bore in the casting which carries this spindle. I'm guessing that in its recent history it's been run with a shaft slopping around in the bore causing uneven wear and allowing the helical gear to foul on the saddle cavity. This is the best picture I could get of the spindle bore trying to show how non-concentric parts of it are:
    20200109_165050.jpg

    The hole at the far end was offset, there were more ridges and grooves than I wanted, so I bored it out so I could sleeve it with a replaceable bronze liner so if it wears out again the casting won't suffer. I used the same jig I used to bore out the knee height spindle bore in the knee, with some modification to take the saddle:

    20200109_170829.jpg

    I spent quite a lot of time with the DRO and DTI aligning the bore to be as close to 30 degrees as possible and lining up the horizontal spindle of the mill to be on the axis to minimize the amount of material to remove. I used my home-made boring bar to clean up the narrowest section of the bore to as close to 1 inch as I could:

    20200109_180313.jpg
    20200109_173258.jpg

    After that I used a boring head to clean up the remaining recesses:

    20200110_170451.jpg

    The boring head came with a MT3 arbor, the mill spindle is INT30, so the reason for the extra length is to get the INT30 ER32 collet chuck to hold a homemade adaptor which screws into the boring head.

    I machined the end of some 1" bar, which would become the new spindle, to accept the helical gear. I used this to check the fit of the gear in the cavity in the saddle. It didn't fit nicely - there was some interference with the side of the casting where the old gear had chewed the saddle. The marks left by the old gear can be seen here:

    20200112_113643.jpg

    So out with a milling cutter to relieve the sidewall to give clearance:

    20200112_114727.jpg

    and at last the gear will spin without fouling. I've not helped things be adding a bronze washer between the casting and the gear which pushes the gear out further, but the washer is supposed to be sacrificial rather than chewing up the cast iron.

    20200112_114534.jpg
     
  17. RobCox

    RobCox Member

    Messages:
    109
    Location:
    Cambridge, UK
    Next job was to sleeve the inside of the bore in the saddle. I wanted a 1" tube for most of its length with a 1.15" shoulder on the outside end. I didn't fancy turning a 1 3/4" bronze tube into lots of swarf, so I made up a short sleeve and heat shrunk it onto the outside of some 1" tube. A shrink fit of less than 1 thou was really easy, the bronze expands a lot when heated with the propane torch.
    20200112_123949.jpg

    I turned the bore first. That was chatter-tastic. It's about 5" long and only 3/4" dia, so the boring bar (a cheapo chinesium one with a carbide tip) was stuck out further than ideal. By messing with the speed (low) and feed (high) I was able to get an acceptable finish. I then put the sleeve between centres and used tailstock pressure to allow it to be driven. Light cuts on the outside to get it to size. Bewteen centres meant I could pop it out to check the fit in the saddle bore.

    20200112_161408.jpg

    Once the sleeve was fitted I turned the shaft down to fit in the bore, made a nut to fit the end to secure the helical gear on and with a lot of honing and polishing, got a nice running fit:

    20200113_130726.jpg
    20200113_175757.jpg

    The largest cavity in the bore provides a home for an FT7/8 thrust bearing, the outside edge of which conveniently just sits proud of the face of the casting. Incidentally, I didn't mention that after boring the saddle I stuck a flycutter in the mill and faced the casting to be perpendicular to the bore.

    I then had to work out what size to thread the spindle for the locknuts to adjust up this bearing assembly. This is where Captain Cock-up turned up...

    The spindle is 3/4", the handwheel I bought inconveniently has an 18mm hole already bored. In order for the ID of the locknut threads to clear 18mm, I was looking at a 40+TPI thread with no margin for error. Did I say I was making it up as I went along...?
     
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  18. RobCox

    RobCox Member

    Messages:
    109
    Location:
    Cambridge, UK
    Time for plan B. To avoid sleeving the shaft inside an enlarged handwheel bore I decided to start again. Step 1, ream the bore in the saddle to make it a uniform 1" (the boring bar had somehow left a 4 thou taper):

    20200118_102441.jpg
    Not having a large enough tap handle to drive the reamer, I had to use an adjustable spanner, maintaining pressure with my other hand to ensure it cut its way forward. Success - a nice collection of chips as it emerged in the cavity:

    20200118_102736.jpg

    And so to the sleeve. Same heatshrink technique to fit a collar on some 1" tube. Bore the bronze sleeve to 7/8" using the 3/4" dia boring bar I used on the casting:

    20200117_154452.jpg

    I bored it a bit undersized and used a cheapo 55/64 reamer that I got off ebay and sharpened to give a nice finish to the bore. I turned up some close-fitting aluminium plugs to drive this between centres to shave the outside down to a precise 1":

    20200118_112207.jpg

    This was the bit I was most concerned about, and the reason I started the first time with a 3/4" bore. I was unsure if the thin wall (1/16") of the tube would sing when cut and leave a lousy finish, but in the end it went really easily. This is the new sleeve in the casting, view from both ends:

    20200118_122135.jpg

    20200118_122152.jpg

    I then re-made the shaft, this time with a larger diameter in the sleeve so the locknuts can have a sensible thread (7/8 - 20TPI). The handwheel will get opened up to 3/4" and eventually get a key. Here's the finished shaft:
    20200119_125150.jpg

    The shaft is undersized in the bronze sleeve (deliberately) by 2 thou. When assembled, you can feel some slop, until you oil it up! The oil forms a thin film stopping the two parts rubbing and doesn't displace, the result being a silky smooth slop free action.

    I've made the locknuts, a spacer and the nut to secure the handwheel on. Here it is, hot off the press this evening:

    20200120_173932.jpg

    Thanks for reading.

    Rob
     
  19. RobCox

    RobCox Member

    Messages:
    109
    Location:
    Cambridge, UK
    Bit of progress today. Made a washer (!) to hold the handwheel on and bored out the handwheel to 0.750":

    20200121_172744.jpg

    Only had 40 thou to come out. Fitted it on to the shaft in the grinder and could finally tighten up the nut holding the gear on so there's now enough friction to allow the gear to drive the table.

    20200121_175342.jpg

    I've made a crude measurement of the backlash. Measured at the circumference of the bearing adjustment locknut, there's about 1/32" of play, which on a 1.946" diameter I reckon equates to about 1.8 degrees. I could shim the rack to tighten it up. I've calculated that with an 87thou shim it'll have zero backlash (ie bind up), so I might make up some 50 thou shims and see how it behaves.

    The spindle has still got to come out and have the excess 0.25" of thread machined off, and there's keyways to cut for the gear and handwheel.
     
  20. RobCox

    RobCox Member

    Messages:
    109
    Location:
    Cambridge, UK
    So the adventure continues...

    I cut the keyways in the table feed shaft and handwheel and drilled the handwheel for the handle .
    20200124_103904.jpg
    20200124_121832.jpg 20200124_125632.jpg

    Once I'd trimmed just under 1/4" off the end of the shaft I got the assembly together. Based on my calculations I turned and ground some 1" dia spacers 50 thou thick:

    20200124_161104.jpg

    Fitted them, only for the gear and rack to bind up. Did some more estimating by fitting just one spacer at one end and seeing how far the table would move before binding and came up with a figure about half what I'd previously calculated. Found some M6 washers which were about the right thickness so I fitted them. The backlash is now an acceptable level. The washers could do with being a bit bigger diameter but they'll do for now. The whole lot is probably going to be coming apart for paint and scraping anyway.

    The saddle travel gibs weren't easy to adjust. If I tweaked them to remove the slop, the saddle would bind when moved towards the operator. The knee ways had been ground before I bought the machine, so I'd left them alone for now, but I might end up scraping them if I can work out how to measure the parallelism of the two dovetail ways. For now I settled for checking the gib as it was an easy fix if it needed doing... and it did. After checking and a first pass it looked like this:

    20200125_122859.jpg

    Being high in the middle was what I had suspected was making adjustment awkward. By the time I'd decided it was good enough for me it looked like this:

    20200125_144122.jpg

    I've started using the Dykem blue as suggested by @spencer427. It's much better than the stuff I was using before, but cleaning up was difficult. I tried white spirit, meths and IPA and all of them would remove it but it just kept on coming. I got through a ton of paper towel wiping down the surface plate. Doesn't come off your hands easy either. I was wearing gloves but still ended up a bit like a smurf!
     
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