Eagle Surface Grinder Build

[RobCox]

With the controls built I've started cleaning up and fixing other bits on the saddle and handwheel. First the oil passages in the saddle. These were full of black crud, s a combination of mechanical means, WD40 aerosol and flushing with way oil has them better.

The saddle has these little pockets front and rear at each end which I'll eventually put some felt in. The hole on the front (that the drill bit is stuck in) is threaded... M6, so probably not original. I'll need to either source some suitable oilers or I'll make some little reservoirs.

I replaced the SHCS acting as the locking mech for the saddle feed dial with one that matches the knee height dial locking screw:



And on to the table travel limiting block. This is a piece of cast ally thats seen better days and is covered in chipped paint:



After a bit of flycutting, filing and sanding it's now got flat faces and is devoid of paint. I turned two spacers to at as the travel stops and fitted them with some 5/16 UNC SHCS to the two holes in the table. Here's the table assembly now in all it's glory:

I now need to sort out the machine protection - the knee screw cover and some bellows for the knee and column ways.

 

[Pete.]

Good work Rob. I have a new-found respect for your work after rebuilding my barely-worn machine. I can't imagine the effort you're putting nto getting stuff fitted without it binding somewhere.

I had to slot the holes on my y-axis gib after machining out the gouges because the gib stopped against the end of the hole and then pivoted which made it bind. Check that yours aren't doing the same.

If you want any dimensions off my bellows and associated bracketry let me know.

 

[RobCox]

Thanks Pete. I'll check the gib to see it's not doing anything like you described. It runs smoothly from the column to about 1 1/2" from the front, then gets tight. I need to dismantle the whole lot and blue up the top of the ways on the surface plate. I checked a fair while ago with my straight edge and they were a bit high at the front. I'm just not looking forward to taking it apart again after all this effort!

I'd appreciate some info on the bellows and bracketry to hold them on. I'm starting from a blank sheet of paper here - I've no brackets or bellows. I've ordered a 200mm wide one from arceurotrade (kerching!) and am hoping that modifying that, splitting it into several pieces, will be enough to do everything. The one I've ordered goes around the dovetail, it doesn't just lay on top like the ebay offerings I've looked at.

 

[RobCox]

And so to the spindle. Some interest has been expressed in seeing how it's arranged and I'll not disappoint. The person I purchased it from had rebuilt it, but for my own peace of mind I wanted to check what goes on inside.

In the words of the title track to that well known musical from the 70's, grease is the word! Loads of it, oozing out all over the place. For starters, I don't want it lubed with grease, I think a constant drip of oil would be better, then if any grinding dust gets in there it will get carried away rather than forming a grinding paste on the bearings. For starters, amongst the collection of bits I bought were two oil cups which screw nicely into the headstock casting above the bearings. Unfortunately someone has at some time modified these (bodged) to add some grease nipples on the top - and didn't get them in straight:



And so to the disassembly. The headstock as received:



Front cover removed:



The front tapered roler bearing slide out easily:



The back of the spindle, before undoing the bolts:



and the gooey mess revealed once the cover was removed:



The bearing shell comes out quite smoothly with a gentle shove on the spindle:



And a couple more gratuitous pictures of the lubrication:

 

[awemawson]

Is there no springing or whatever to allow the spindle to grow as it warms? Usually one taper bearing stays fixed and the opposing one can slide a tad.

 

[RobCox]

So at this point I used a bronze rod and a soft blow hammer on the inner part of the rear bearing to drift it off the shaft. I did try a puller, but those 3 legged things are awkward inside a casting and I was getting fed up of being covered in goo. Once it was all apart, over to the "parts washer":



and more residual goo to clean out of the front of the headstock:



The shoulder inside the bore is an aluminium ring thats just tapped in, although from the scars on the other side it's clearly put up[ a fight at some time. I tapped this out too. I missed out needing to remove the pulley as the spindle was slid out. It had a grubscrew which has chewed some nice rings in the spindle opposite the pair of woodruff keys. On inspecting the pulley, I spot something else to remake:



Not much of a "V" left, more a "U". It's only a chunk of ally, this will be remade. At the front end, I checked the fit of the bush around the spindle. I'm guessing the function of this bush is to slow down the ingress of grit into the roller bearings. This one won't. Another little job.



The tapered roller bearings are Timken. They're not the smoothest bearings I've felt, so I've got to decide whether to fork out more dosh to replace them. Looks like about £40 a pair for FAG or £50+ for Timken. Ouch.



And so to the overall spindle assembly:

The bronze sleeved bushing was fitted by the previous owner. Not sure what it's function was - I can't imagine those bearings need any additional radial support. I won't be putting that back in. On the back of the spindle is a cap which I assume in conjunction with the adjusting screw in the rear housing preloads the bearings. It's aluminium, rubbing on a steel shaft. I'll probably fit a pad of bronze in there which will provide a better running surface.

So there we are. Front housing needs cleaning and re-sleeving. The bearings might get changed. The pulley needs replacing. The rear thrust pad will get a bronze insert and the rear housing needs cleaning up. The adjusting screw will get changed too, not the it'll ever get seen but the screwdriver slot isn't too tidy and the locknut won't come off as the threads are a bit mangled.

Enough for now. Thanks for reading.

Rob

 

[RobCox]

Is there no springing or whatever to allow the spindle to grow as it warms? Usually one taper bearing stays fixed and the opposing one can slide a tad.

You've got me wondering if there should be some sort of springy washer between the front bearing and the front housing. The bearing housings slide withing the casting without being too loose. All I've got to go on is what you see above.

 

[RobCox]

I investigated the motor that came with the grinder tonight. This really is the gift that keeps on giving, giving problems that is. The 3 1/2" pulley was worn down to a wall thickness of about 1/16". I could tell from the pieces of shrapnel after I'd persuaded it to come off with my home-made puller (whose original purpose was to change bearings in my mini lathe 5 years ago).



It didn't really want to come off and even with a plate spreading the load across the back of the thin ally, it fell to pieces. Much struggling later the pulley and a sleeve it had been forced over came off to reveal these delights beneath:



Theres more damage on the other side too. I've removed the rotor and now have a decision to make. Either turn this down and heat shrink a sleeve over the damaged end or find some kind soul to build it up with TIG so I can machine it back. Then there's the bearings to replace and the star connected windings to fish out to rewire it as delta for a 240V VFD. Some cleaning will also be needed as the black dirt that fell out when I separated the ends has stained everything it touched. I guess its probably nice and abrasive too.

Alternatively I can buy a new motor. I must admit thats looking like the better option, though I haven't priced it up yet. But hey, its only money! New spindle bearings and a wave washer are on order to sort out the spindle, the new bellows for the saddle ways have arrived and look very nice, and I've started work roughing out a new pulley for the spindle. I'm in too deep to bale out now!

 

[RobCox]

An update on the state of the motor:

I decided that I couldn't weld the spindle to build it up, but I have a Bullfinch propane torch so I could use that to braze it up. Additionally, whilst the motor was in bits I'd start with modifying the stator winding configuration. The third thing to sort out was new bearings, as they'd have to come off before I started cooking the rotor anyway.

First thing though, a thorough clean. The black dust that poured out of this thing stained everything badly:



I got the loose dust out with the vacuum, then poured IPA through the casing to wash as much of the rest of it out as I could. The rotor and bell housings were easier to deal with. At this point I could see where the winding connections were so I fished them out from under the lacing cord:



I used my old multimeter to work out which start belonged with which end and labelled them up, making sure I knew which wires were originally on the star point, then rewired it as a delta config. I soldered some wire on to each connection and used heatshrink to secure it all together. Finally threaded the new flying leads under the lacing, crimped on some eyelets and connected them to the terminal board (a bit blurry I'm afraid):



And so to the rotor. The Bullfinch torch will melt bronze but it's slow. I started out with the biggest burner (I think it's a 6kW) but most of the heat seemed to miss the shaft, so I tried the standard one, which worked much better. This is the shaft once it had cooled down. I didn't get all the grooves filled with bronze as the smaller ones fill with molten flux and vanish, only to reappear when the flux is chipped off later:





And on to the lathe. The centre hole on the repaired end of the shaft was beaten up and of course, full of flux. I held the other end of the shaft in a collet and rotated it in the collet to find the lowest runout position, measured on the bearing journal. I then set the steady rest up on the bearing journal and re-cut the centre hole. I could then support the end of the shaft and turn down the diameter:



The shaft started as 5/8", but as I'd be making a new pulley and could have any bore size I wanted, I sacrificed 25 thou diameter to get the shaft looking clean:



I milled a 3/16 keyway with the rotor held in a spindexer on one end and the footstock on the other. Of course, the cutter I picked out was blunt and found that the bronze hadn't taken that well on one side of the shaft. The bit laying on the mill table was what was originally in the hole. Disappointing, but the rest of the shaft was ok so I'll live with it, rather than go through the whole process again for something that'll probably never be seen again:



New bearings fitted. The originals were open frame but it won't get greased very often so I went with 2RS versions. Here's the reassembled motor, with the 3 1/2" pulley I've turned for it:







When the VFD arrives, I'll find out if it works!

 

[mtt.tr]

Very smart.
Being interesting to see how well the motor runs.

 

[RobCox]

The VFD arrived this afternoon. I connected it to the motor, set the "speed" to 50Hz, the acceleration time to 15s and deceleration to 20s.

The motor spins up very nicely, no unpleasant noises or anything that suggests its wired wrongly. Success!

I took a video of it starting and stopping but have no idea how to upload that here.

 

[mtt.tr]

The VFD arrived this afternoon. I connected it to the motor, set the "speed" to 50Hz, the acceleration time to 15s and deceleration to 20s.

The motor spins up very nicely, no unpleasant noises or anything that suggests its wired wrongly. Success!

I took a video of it starting and stopping but have no idea how to upload that here.

Really pleased it works, having slow start is a positive as without mine spins the wheel, inspired me to do my motor now when i have the time maybe


cant really get it wrong unless you loose the star point, nothing like a motor with no markings to then have to find the correct sequence

 

[Seadog]

I took a video of it starting and stopping but have no idea how to upload that here.

Upload it to Youtube and then share the link.

 

[RobCox]

Finally got around to uploading the video. Enjoy, thats 26 seconds of your life you won't get back!

https://youtu.be/LRFUIWEmgcw

 

[mtt.tr]

Finally got around to uploading the video. Enjoy, thats 26 seconds of your life you won't get back!

https://youtu.be/LRFUIWEmgcw

Congrats, what vfd did you opt for?

 

[RobCox]

I've been doing more work on getting the spindle sorted out. I made a new pulley for the spindle. Second attempt actually. The first one might have been ok but I think the V groove was a bit deep:



The grubscrew that locks it in place is next to it above. Despite the shaft being hardened, there's evidence of where the previous grubscrews were fitted, having chewed little circular grooves on the surface. I stoned off the burrs and to stop it happening again I've drilled the grubscrew and fitted a small brass plug. As the pulley is around 1/2" thick where the screw fits theres plenty of length on the screw to do this.

So, with the new bearings pressed on, here's the spindle with almost all of it's components in the order they fit:

Just behind the bearing on the right is an aluminium collar which is slightly tapered and serves to keep debris out of the bearings. The previous owner had fitted a bushing which I didn't want to reuse for the rear (LHS above), so after this photo was taken I made another one from some ally rod. In the pic below it's about to be parted off before being reversed onto a shoulder cut in the original material so the face could be cleaned up:



And so to the assembly. With all the bearings "pressed" on (I don't have a press, so they were tapped on being careful to only drive them on the central collar) the spindle will work its way into the headstock casting like this:



The belt needs to be fitted at this stage, to avoid later frustration! Once in, the bearing shells can be slid in, the front flange bolted on, then the wave washer fitter at the rear and the rear flange, with the preloading "piston" (couldn't think what else to call it) in place, bolted on. I remade the preload adjustment screw and cleaned up the nut. Here are views of both ends, inside and out:






The headstock has been refitted to the column, and its beginning to look a bit like a surface grinder again!

Thanks for reading.

Rob

 

[RobCox]

Next problem to tackle are a couple of bits of damaged or modified aluminium. The lid was modified by the previous owner to add an oil port for the rear bushing that I've removed:



I'm intending to machine up a piece to loosely fit in there, then use some aluminium brazing rods with the propane torch to glue it together.

The second piece thats damaged is the wheel guard. The original bolt hole was stripped and a new one drilled and tapped. The locating ears have suffered sometime in the past too.



Not quite sure what to do here. Leaving it alone is an option, but given how much else I've done to this machine, I probably won't.

 

[RobCox]

Congrats, what vfd did you opt for?

I've gone for a WEG inverter from inverterdrive.com. I could (ie. should) have got a CFW100 0.75kW model, but for some reason confused 1HP with 1kW, then opted for the 1.5kW CFW300 at considerably higher price. I may still buy the CFW100 as I don't need lots of control inputs (it'll be fixed speed with on and off switches) and I'll use the CFW300 to drive the shaper when I finally get round to refurbishing that.

 

[RobCox]

Today's progress...

Filled in the unwanted hole in the headstock cover plate. I started by machining and filing the round ended slot to have square corners, then machined up an offcut of aluminium to fit:




Then off to the garage to fire up the propane torch and use some aluminium brazing rods to glue the two parts together, resulting in this unholy mess:



Unfortunately I got the edge of the casting a bit hot so had to add more material to make up for the bit that sagged out the bottom. I definately need more practice with the torch. Anyway, after some milling with the poor man's CNC (move X and Y at the same time to try and mill a curve) followed by the boring head to cut the clearance for the mounting hole and some filing, the piece now looks like this:




The phone camera has accentuated the difference between the grubby cast metal and the new shiny surface. I was very pleased with it - it looks better in the flesh so as to speak. The inside was also cleaned up, totally unnecessarily so, as you can't see it when the plate is fitted to the headstock. I did flycut away the material that sagged where I overcooked it:



The casting is really porous and is full of oil. It smoked for ages after I'd finished brazing it up.

Second achievement of the day, getting the motor fitted. I want to remake the mounting arrangement as the motor weight is pivoted on the threads of two bolts, which aren't designed for this and the consequences are:



Anyway, I reassembled it to check dimensions for whatever I come up with. Here's the motor in the base:



The wood blocks lifted it most of the way to it's mounting height, which makes it easier (still not easy!) to feed the bracket fixing bolts from the outside of the base, the far side looking at that picture, and fit a nut on. I ran the motor for a bit - of course it went round the wrong way. I believe the spindle should rotate in the same direction that the spindle nut tightens, so if the wheel jams the spindle nut will loosen and prevent something bad happening.

When the time came to stop the motor, it coasted down a bit then stalled. Turns out the rear shield I turned didn't have enough clearance over the shaft, so all apart again, trim the shield to have 10 thou more clearance, stone the bits of ally off the spindle and clean and reassemble.

A question for anyone who's got one of these grinders or something similar. I assume there should be some sort of gasket between the lid of the headstock and the headstock casting, as the aluminium casting isn't very flat and hasn't ever been machined to make it so. There's probably 20 thou gap in the middle to let grinding dust at the spindle.

Thanks for reading.

Rob

 

[ronan]

Did you get the spindle dynamically balanced Rob ? What speed does it spin at ?