Eagle Surface Grinder Build

  1. RobCox Member

    Cambridge, UK
    I've been hanging about on this forum for a while and have enjoyed reading through the various rebuild and refurb threads on lathes and mills, so I thought I'd add my current project on here by way of something slightly different.

    I acquired an Eagle surface grinder, partially assembled, but mainly a collection of fasteners and worn out bits needing replacement to get it back to a useable state. After diassembling the castings so they could be lifted in and out of my car and collecting together the remaining parts, this is where I started:

    SG Base.jpg

    SG components.jpg
    What I have here is a collection of original, repaired but worn out and partly restored bits. I have no manual or assembly drawing so I'm intending to put it together, making whatever bits I need as I go on. I was told when I acquired it that the column and knee had been professionally ground and that the table was worn into a bow as expected. Fixing this up is going to require me to learn new skills like scraping, but within a year or two I should have a new toy in the shop!

    ronan, fizzy, Kayos and 3 others like this.
  2. eLuSiVeMiTe

    eLuSiVeMiTe Forum Supporter

    Bedfordshire England
    I belive another member here picked up one of these recently. Worth a search for the thread.
  3. RobCox Member

    Cambridge, UK
    The first step was to get the main castings out of the garage and in to the workshop. I made room by relegating the woodturning lathe to the garage instead. I set it next to my bench grinder and started determining what needs fixing:
    SG first assembly.jpg

    The list, so far, of what needs fixing, is:
    - The main spindle has been rebuilt by the previous owner and doesn't seem too bad. I assume the minor amount of play will tighten up once it runs and the bearings get warm
    - All three control spindles (knee height, y axis feed and x axis feed) need machining
    - The knee height spindle is worn by about 20 thou, the casting it runs in is wallowed out
    - the knee height screw is in good condition but the bevel gear that drives it is a loose fit
    - the rack that drives the x axis is worn out in the middle
    - the helical gear that drives the rack seems in good shape but the spindle is a mess
    - the y axis feed screw looks like it's been replaced before (it's a 60 deg, not acme, thread) but I was given a length of 3/4" acme rod with the machine which I intend to use.

    I'm sure more will come to light as I progress. For now, I've made a start on the knee height, which I'll post details of as and when I get time.
  4. Blackolive

    Blackolive Member

    uk lancs
    have fun and welcome
    ronan likes this.
  5. gaz1

    gaz1 Forum Supporter

    looks to be a nice project I had looked at that machine a while ago
  6. RobCox Member

    Cambridge, UK
    Some of the progress below happened a while ago, but given all the faffing about to get the job done and the limited time I have at the mo, it's taken a while to make some useful progress.

    Below is the bore in the knee that the height control shaft runs in. It's wallowed out so the shaft slops up and down. The bore is worn up and down by 10 thou more than it's worn side to side and the shaft that rides in it has a distinct step where it's worn.

    SG knee height shaft bore.jpg
    The oval shape isn't that obvious from looking at it, but is easy to measure (and to feel the slop in the shaft). The fix I came up with was to a) bore out this casting to accept a bronze sleeve, b) fit thrust bearings at each end rather than have the pinion run against un-machined casting, and c) make a new shaft with provision for locknuts to make bearing adjustment possible.

    To bore this out, as I only have an Elliott 00 omnimill, I had to make a fixture to mount the knee on the table hung out far enough so I could make use of the full Y axis travel. There's insufficient Z height to use the quill to do the boring, so I bought an INT30 to ER32 chuck to hold tooling in the horizontal spindle and made a fixture with some box section and rob I had kicking around:

    SG knee to mill table fixture.jpg

    The knee was mounted on the fixture and aligned as close as I could get to 45 degrees, checked with the DRO and a dial indicator:

    SG knee on mill table.jpg
    The rod poking out the ER32 chuck is a homemade boring bar. It needed over 6" of travel, opening up a nominal 3/4" bore to 1". The cutting bit was a piece of 6mm HSS rod secured with a couple of grub screws. I needed 3 different bits as the bore dia increased. Once the 1" bore was complete, which took ages as the boring bar has a tendency to chatter so I had to run it at less than 100rpm, I cut the counterbore for the thrust bearing on the inside of the casting. All adjustments to the cutter had to be done inside the casting - not easy when you've got big hands:

    SG knee internal boring for thrust bearing.jpg
    Dr.Al, spencer 427, Pete. and 11 others like this.
  7. RobCox Member

    Cambridge, UK
    I bored the outside face as well to take an FT 3/4 bearing which I had lying around from the restoration of the Omnimill. I machined up a piece of bronze tube to 1" OD, 3/4" ID and fitted it in the bore. It's a nice interference fit. It had to come out several times (which involved using the old shaft as a side hammer) to have a couple of recesses for securing screws and a hole for an oil port.

    SG knee height bore sleeved.jpg

    The threaded hole that the bearing recess has broken into is for the securing screw for the metal bar for the marker of the graduated dial, and won't be a problem.
    spencer 427, ronan, indy4x and 4 others like this.
  8. RobCox Member

    Cambridge, UK
    And so to the new shaft. I could have modified the old one, bored the bronze bush to less than 3/4", but I preferred to start from scratch as I was going to fit a new handwheel (the handwheel bore started bigger than the end of the shaft).

    The shaft was machined from EN8 rod, between centres. The surface grinder has imperial threads so I stuck with imperial measurements (the fact that my lathe is imperial also sways this decision). Machining this shaft gave me the first opportunity to use the fixed steady. A travelling steady would prob have been better but I don't have one.

    SG shaft being turned.jpg

    I tend to use HSS tooling, having done woodturning for 20+ years prior to taking up machining, as grinding toolbits comes as second nature. This material is a bit awkward to get a decent finish on it without carbide, so I usually machine to within about 8 thou oversize and reduce to size with a shear tool, which gives a very nice finish.

    The completed shaft needs woodruff keyseats cut for the pinion and the handwheel. Both are 5/8 x 1/8. Being too tight to cough up for an HSS tool that I'm just as likely to snap first time out, I bought a foot of silver steel stock for about the same money and rolled my own. At this point having a tool & cutter grinder (Union - another strip down and rebuild job) comes in very handy to get all of the cutting edges on the same diameter.

    Keyseat cuttting.jpg
    The end above is for the pinion. Fits like a glove, but then, as I'd cut about four keyseats in scrap pieces first to practice, it should have done!

    The locknuts that set the bearing adjustment have a dual purpose, the second being to carry the graduated dial. Here's a shot of the shaft mounted in the knee with the locknut and dial, also with the bent bit of metal which serves as an indicator. I'm not wild about the look of this indicator, but it is original.

    New knee shaft first assembly.jpg
    Finally a close-up of the two locknuts and graduated dial with a knurled locking bolt which replaces the slotted head screw. The locknuts have slots to accept ER32 spanners to jam them together. The 9/16 UNF thread is for the nut to secure the handwheel, but neither the woodruff keyseat nor the securing nut have been made yet.

    Close up of knee graduations.jpg
    And that's pretty much up to date.

    Dr.Al, spencer 427, ronan and 13 others like this.
  9. Pete.

    Pete. Member

    Kent, UK
    That was a brave undertaking, well executed.
    ronan, indy4x and mtt.tr like this.
  10. indy4x

    indy4x Forum Supporter

    Pontypool, South Wales. UK
    Wot @Pete. said, especially the unconventional setup to get the machining done, like it lots
    Hopefuldave likes this.
  11. RobCox Member

    Cambridge, UK
    Next part of the puzzle...

    The bevel gear that engages with the pinion on the shaft I've just sorted and drives the knee height screw has a couple of issues.

    The bore of this gear is spot on 750 thou and does not appear worn or ovalled, but the top of the knee height screw shaft is about 8 thou smaller diameter. Whilst it makes assembly easy, the gear rocks around a bit and as there doesn't appear to be a Z axis lock on this machine and I'm not confident that the knee won't shift in use due to this slop. The screw shaft doesn't appear worn, so it may have been this way from new.

    The gear has a 1/8" key and a grub screw over the key to secure it to the shaft. In a previous life someone has gronked on this key to try and tighten out the slop with the predictable result given that this gear appears to have been cast:

    Bevel gear grub screw thread.jpg
    There aren't many threads left and the grubscrew doesn't tighten straight. To fix this, I've considered various options. I could wedge some shim around the shaft but that feels like a bodge given the effort I've gone to to make the other shaft right. I can't remake the screw (well I could, but I don't think I'd end up with something that would be polished smooth like the existing one) or, what I am considering, is to bore out the bevel gear, machine a plug to be a very light interference or sliding fit secured with loctite, bore out a new bore to match the screw shaft and cut a keyway & drill a locking screw thread opposite where the current one is. If it all goes south I'll have to buy a new 2:1 bevel gear set.

    I don't have the facilities to braze up the grub screw hole (only have propane-air and I don't think it would get it hot enough) and it would still leave the bore needing attention, so I'll probably leave the old grub screw thread alone.

    Any thoughts?

    spencer 427 likes this.
  12. Seadog

    Seadog Forum Supporter

    NE London - UK
    Oxypropane will be OK. I've silver soldered a small cast iron piece using my MAPP torch. Just make sure you have it surrounded with fire bricks to retain the heat.
    Hopefuldave and slim_boy_fat like this.
  13. RichardM Member

    Seconded for fire bricks - I have brazed with Mapp gas and fire bricks (old gas fire radiants) before.
    ronan and Hopefuldave like this.
  14. Milkybars

    Milkybars Member

    Robcox, I also have some Fire bricks you can have for free ..in ilford at the bottom of the M11
  15. RobCox Member

    Cambridge, UK
    Milkybars, thank you very much. I work just up the road in sunny Harlow at the mo, so shouldn't be to difficult to arrange a trip to Ilford.
  16. RobCox Member

    Cambridge, UK
    To finish off the knee height shaft assembly, I broached a keyway in the new handwheel using the quill of the mill and a toolbit ground to 0.125" width. The old woodruff key was a bit of a loose fit (and was chewed up) so I made a new one and stoned the sides down till it was a snug fit.
    Broaching keyway in handwheel.jpg

    The finished handwheel assembly, minus the handgrip which was still to have a hole drilled and fitted when I took the picture is:

    Handwheel fitted.jpg
    The nut is a bit of a random size as it was turned from an offcut, but I liked the look of it so didn't want to mill it down further to fit a 22mm socket.

    Now that the shaft is working I can see the effect of the slop in the bevel gear and it doesn't look good, so it will definately need sorting out. About 1 1/2 divisions of slop on the scale (I think thats 0.015mm) before the knee screw will turn, and you can see the gear rocking, so it won't last long before something wears out or breaks.

  17. RobCox Member

    Cambridge, UK
    Back from holidays and a bit more progress.

    I bored out the bevel gear from 0.75" to 1" to remove all of the old keyway. I made a sleeve out of an offcut, bored out to 0.65" (shaft is 0.741") and a shade under 1" dia. I drilled out the broken grubscrew thread from the side of the gear so I could fit a steel plug which will hopefully allow the grubscrew thread to be stronger than the cast was.

    Bevel gear repair.jpg

    I silver brazed these parts together - my technique is somewhat lacking as its over 35 years since I last did any silver brazing when I worked one summer for a bicycle frame builder. I had trouble getting the braze to wet the material as I'd done too much of a good job removing flux from outside the joint. Second attempt it worked but I didn't manage to get the braze to wick all the way up to to tooth end of the bore. The joint might have been a bit tight, as when cleaned up, bored to 741 thou and a keyway cut, the brazed joint is really thin:

    bevel gear keyway.jpg

    I cut the keyway on my mill. I've got a DIY spindle lock which makes use of the quill depth stop - a bored out piece of aluminium plate clamps round the spindle and is stopped from rotating by a screw I made to replace the depth stop screw:

    Spindle lock.jpg

    After a bit of fettling with some abrasive to get the gear to slide onto the knee screw shaft (which is slightly tapered - probably due to the gear slopping) I got the knee assembly back together. The nut didn't line up with the mounting holes in the plate on the base as the knee ways had been professionally reground before I acquired the maching. I sorted this by fitting the plate onto the base, rotating the nut 180 degrees and transfer punching the new bolt positions. Having drilled the new bolt holes I bored out the plate to clear a shoulder on the nut that projects into the plate:

    Base plate boring.jpg

    Then finally I got the whole assembly back together. With the gib adjusted, the knee movement is really smooth, with a backlash (as indicated on the dial) of about 1 thou:

    Knee assembly.jpg
    Very pleased with the result. Now on to the Y axis...

  18. Parm

    Parm I have fun doing stuff

    Top work, good write up too :thumbup:
    ronan likes this.
  19. awemawson Forum Supporter

    Excellent job you are doing there ;)

    I sold my Eagle a good twenty years ago to a friend who then moved to France, and when he returned he sold it to a chap who came all the way from Poland to collect it and other bits of his workshop - a well travelled machine !

    slim_boy_fat likes this.
  20. RobCox Member

    Cambridge, UK
    Thanks for the comments and I'm glad people are reading this.

    So to the Y-axis/saddle feed. The photos below are my starting point after extracting the bushings from the saddle and rounding up the other bits from the pile of components . The screw has clearly been repleced in the past with a V-thread and as I was given a couple of feet of 3/4-10tpi acme rod when I picked up the machine, my intention is to redesign/remake the spindle, adding thrust bearings as I did with the knee height shaft.

    Starting point.jpg

    The bushes/washers at the front may or may not belong to this.

    To help get the V thread nut out of the casting I cut a length of the old spindle off to give me something to hit to drift it out. Couldn't move it cold so cooked it with the Bullfinch and out it popped - looks like it was retained with loctite.

    I had a piece of bronze tube, just over 1" with a 0.5" bore, perfect for the 1" hole in the nut casting. I started off by boring the tube out for threading. Several mistakes here - would have been easier to do the outside first, then clamp in the 4-jaw with ally spacers and dial it in, rather than thread, then have to make an acme threaded arbor to hold it true (ish) to finish the outside. Second mistake was to start working out the bore size I needed on the fly in the workshop, get confused and bore to 630 thou rather than 650 for the ID (I knocked off the 10 thou clearance, twice, to arrive at this size).

    Not having a 10tpi acme insert, nor a tap, and having a T&C grinder and some HSS rod I ground up a toolbit. The grinder does the angles nicely and the acme rod and micrometers gives the width of the end:

    ACME toolbit grinding.jpg
    The resulting toolbit fits in a shop-made boring bar.

    ACME toolbit.jpg

    My technique for cutting the thread is to have the nose of the tool undersize, touch off, plunge to depth (in steps, not one go!) then as I have the compound set parallel to the axis, take full depth cuts advancing the topslide a thou or a half at a time until I have the fit I want on the screw.

    Thread cutting.jpg

    The outside was machined on a custom made arbor (didn't want to waste the rod) and a 1"-20tpi UNEF thread cut on the outside for a nut to retain it in the casting.

    Finished nut.jpg

    With a matching nut machined out of a brass offcut to retain it and a divot drilled for the anti-rotation grubscrew we arrive at the completed assembly:

    Finished nut assembly.jpg
    Thanks for reading.

    Shox Dr, Dr.Al, Pete. and 10 others like this.