Thread: I have the Power (Surface grinder)

Originally Posted by PDW

I think you *should* pull the spindle apart just so you're happy all is well there.

Take pictures. Lots of pictures......

By popular demand...
The spindle is not that complex although it has some interesting features to it.
This is how it starts. There is a grease nipple that mounts on the front and guides grease through various grooves to lubricate the ways. The ways are covered by covers but these were one of the first things to come off.
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The pulley end is simple. Remove the screw at the end, remove the pulley, Woodruff key, labyrinth seal and that is it.
P1020228 (Medium).JPG

The wheel end is a little more complicated. The holder for the wheel screws onto this tapered shaft (with a LH W/W SHCS - try finding one of those as a spare part). The pre-tensioning for the bearings is next. As well as acting as a lab seal it preloads the bearing - LH thread too. I was a bit concerned as the thread had a bit of damage to it but some work with a needle file seems to have fixed things. After that a retaining flange is removed and the shaft can be tapped out. Surprisingly the bearings are greased but there is no way of recharging the grease.
P1020229 (Medium).JPG P1020232 (Medium).JPG

All up the spindle assembly looks something like this -
P1020234 (Medium).JPG

I am now waiting on replacement angular contact bearings. They are Fafnir ABEC 7's but "relatively" cheap I'm told. I need to think about the bearing arrangement some more because when I took them out there was an angular contact at the front with a thrust bearing (good so far) but at the rear there were two thrust bearings. Not sure if that is a mistake or meant to be that way.
Today's interesting feature -

There is a notch in the front bearing retaining flange (as below) and a small hole. A piece of copper pipe goes in the hole and if you look at the group photo above there is a knurled nut on the side of the housing that acts as a tap, letting fluid from the reserviour on top of the spindle flow down. Peter suggested that it was for coolant. However, the spout points it at the back of the wheel mount. The picture does not show it well but the annular groove shown in the second photo slopes back into the part. There are 8 fine holes at the apex of this grove that are through holes. I'm wondering whether a small amount of fluid in this groove helps balance the wheel?
P1020231 (Medium).JPG P1020235 (Medium).JPG

Michael

Originally Posted by Michael G

There is a notch in the front bearing retaining flange (as below) and a small hole. A piece of copper pipe goes in the hole and if you look at the group photo above there is a knurled nut on the side of the housing that acts as a tap, letting fluid from the reserviour on top of the spindle flow down. Peter suggested that it was for coolant. However, the spout points it at the back of the wheel mount. The picture does not show it well but the annular groove shown in the second photo slopes back into the part. There are 8 fine holes at the apex of this grove that are through holes. I'm wondering whether a small amount of fluid in this groove helps balance the wheel?
Michael

It was just a guess as I couldn't see any other reason why you'd want to introduce liquid there. But the reservoir is small so..... ?

I now have mine in pieces as well. Not the spindle as yet - you can always tell the pioneers, they're the ones lying in their faces with arrows in their backs - but the rest of the machine. The amount of built up grit in the column plus an excess of grease in other places decided me so I loaded up the blast gun with kero and let rip. Should be a nice patch of dead grass as a result too, another bonus.

The paint job has held up very well considering the age and my treatment of it to get it all clean. As expected I decided to bin the original switch and wiring. I prefer my 415V cables to actually have functional insulation on them.

The column ways look fine so the shielding must work. There is some wear in the inverted V ways of mine but I don't really plan on doing anything about that right now. I'd need to make up some prismatic spotting patterns and get them cast or hack off a few strips from some CI flats I have lying around then mill/scrape them. All a bit hard for me at the moment, too many jobs running.

Why are you replacing the bearings? Are they worn or is it a case of just because you can while the thing is in bits? And are you going to use the ultra expensive Kluber goop when you put it all back together?

Interestingly a lot of the SHCS appear to be metric. I wouldn't have expected that. Certainly my metric Allen keys fit very nicely, haven't checked with a thread pitch gauge.

I appear to have a spare cross slide screw & nut and possibly 2 spare gears for the vertical feed in the parts collection.

PDW

Originally Posted by PDW

Why are you replacing the bearings? Are they worn or is it a case of just because you can while the thing is in bits? And are you going to use the ultra expensive Kluber goop when you put it all back together?

Apart from a general rule that I have about replacing belts and bearings on old equipment when possible, the trouble with angular contact bearings is that they always feel gritty. Once I had the spindle shaft out (as per the picture) I though the bearings felt worn and should be replaced although I couldn't see any numbers so did not know what they were. Having removed them the thrust bearings feel fine so they will be reused. I was trying to remove each bearing carefully and then one of the ACs came apart (but I've found 9 out of the 10 balls!), so a replacement is needed there anyway. I'm only going to use Shell Gadus grease. Kluber is too expensive for my everyday pursuits

Michael

Originally Posted by Michael G

Having removed them the thrust bearings feel fine so they will be reused. I was trying to remove each bearing carefully and then one of the ACs came apart (but I've found 9 out of the 10 balls!)

Heh. See previous comment re pioneers.....

I disassemble everything inside trays to minimise the opportunity for small parts to migrate to the machine shop black hole. Habit from playing with antique guns years ago where there are a lot of small unobtanium parts that have a great affinity for black holes. This isn't always successful, but it helps a lot. Some time ago I managed to pick up a large number of those stainless trays you see in Bain Marie bacteria cultivators err food warmers. Not only do they help in disassembly, they ensure that you can lose all the parts in one go when you file the entire tray and then can't remember where it went.

My spindle actually feels fine so ATM I'm undecided about its disassembly. Be a good opportunity to repack it if I can avoid losing any of the parts.

PDW

The copper pipe and groove in the wheel mount is for coolant. I have a svend jakobsen SJ12 grinder that is about the same vintage as yours and it uses the same system for coolant. I don't have my grinder working yet so i don't know how well it works, i think its just a drip feed system and not flood coolant like modern machines have.

Originally Posted by snapatap

The copper pipe and groove in the wheel mount is for coolant. I have a svend jakobsen SJ12 grinder that is about the same vintage as yours and it uses the same system for coolant.

Welcome to the forum and thanks for the information

In the meantime today I got a bit side tracked. Peter's grinder has pipes in the bases of the slide oil wells but mine does not. I was thinking about this and thought that it shouldn't be too difficult - so today I put those thoughts into action.
I bought some copper tube from a hobby store. They sell it for all sorts of things but I just wanted something I could bend easily.
The oil wells I'm talking about are these - there are two per slide and they have a spring loaded piece of felt in them that sits in a pool of oil and so wipes a thin film onto the slide, From the underside of the casting they look like blocks of casting, as per the second photo. It is deceptive though as the walls on those blocks are 1/2" thick.
P1020187 (Medium).JPG P1020236 (Medium).JPG
To work out how to drill the hole I had to transfer the dimensions of the well to the back of the casting. It turned out that the bottom of the well was below the surface of the back, so I had to drill at an angle to get to the well. I also wanted to land in a particular spot (the semi-circular region seen on the front) and right at the bottom of the well - so I worked out where the hole had to start, used some trig to work out a drill angle and away I went.
Shown below are the results for the first hole

P1020237 (Medium).JPG P1020240 (Medium).JPG

Bending the tube did not take much effort but there is a trick - put something in the tube to stop it crushing. I have used nylon whipper-snipper cord and here used some electrical wire. Works well with nylon tube too if you have to heat it for sharp bends. The harder the better though, so the whipper-snipper cord would have been better than the wire I used if I'd had some the right size. I then bent it around a form to get a nice radius.
P1020243 (Medium).JPG P1020245 (Medium).JPG
I marked the tube with the straight I needed to insert into a hole and then put another mark 30mm back so that if I had to work out a length or bend radius, I had a reference point. Once I had 2 holes and a tube with 2 bends in the right places, I "glued" it in place with bearing locking compound. The first photo shows a tube in place (checking for clearance) and the next shows all three tubes chained together. The cross tube was tricky to get in because there was a rib in the way, so I had to drill a hole to get the tube through.
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Two essential tools that I used were the inclinometer to check the drill angle and a squirt bottle to flush chips etc out of the holes. These are available in marine shops as they are used to prime meths and kero stoves (LPG being heavier than air is a no-no as it collects in bilges before going bang)

P1020250 (Medium).JPG

Finally, to get the oil in I fitted a 'Gits' oil pot. It also acts as a level indicator as when it is full to the brim, so are the oil wells.
P1020251 (Medium).JPG

I'll see how the levels have evened out in the morning but it seems to work - so on this machine now grease nipples for grease and the oil pot for the horizontal ways.

Michael

While I'm waiting for the bearings, I found this which may come in handy for some -
http://www.brg-catalogues.com/default.html
If you go to the F-J page there are a bunch of catalogues including one that lists the Fafnir letter code

In the meantime, here is a diagram of the grinder spindle. (the cavity in the casting above the spindle is the coolant reservoir that was being discussed)
Spindle (Large).jpg
Now - at the wheel end, the bearings are fixed to the shaft with the threaded green nut and fixed to the housing with the retainer. All good. There is a thrust bearing to take axial load and an angular contact to look after radial (and axial) load. Seems a bit redundant but that's what it is.
On the pulley end the bearings are fixed to the shaft through pressure from the bolt securing the pulley, and are free to float in the housing within limits. No problem here either as that way any heat build up does not distort the shaft.
The bearings here are the issue though. They are marked as both being thrust bearings (although these are Fafnir bearings so who knows what they really mean ). They do seem to have a degree of radial constraint but I am wondering whether one of them should be another AC or at the very least a deep groove.

Thoughts/ opinions anyone?

Michael

Snuck out and did a little more this evening. As I reported before, the front bush for the traverse was missing, so a new one of those was needed. The back bush had worn a bit so it was no longer 9/16"(nom) and the screw that secured the traverse wheel was missing - so I decided to make up a new shaft (7 thou bigger) - the old one was a ring in anyway, a new screw and a new bush. While doing that I realised that the skew gear was sized for the old shaft and not mounted properly anyway, so a new skew gear was in order.
The blank was a straight forward turning effort. In fact I made 2 - one for a 17t gear as per the original and one 18t as the centre distance looked larger. Then it was time to mill. I like cutting gears and I find helicals even more interesting (takes all sorts).
There is some maths involved so I've developed a spreadsheet to do that bit. The rack that they mesh with is 16DP but because of the helix angle, a different cutter is used (in this case 18DP) and it is sized for the "effective number of teeth", so this was cut as if it was a 43t gear (even though it was 18)
P1020254 (Medium).JPG

The mill table is swung around to the helix angle and then a gear train driven from the table leadscrew drives the worm on the dividing head. The DH is index as per normal. Mine is a metric mill, with a 200mm lead on the table so part of my spreadsheet works out the lead ratio so that I can then use the Machinerys Handbook to tell me the appropriate sized gears to use. In this case to get the DH moving in the right direction I had to put an idler gear in to reverse the motion (with a dodgy bracket to secure it).
P1020257 (Medium).JPG
Once the ratios are set cutting is easy. As a first I used an expanding mandrel (tip - have the cutter pushing the work on the mandrel), although I'm not sure I'd do that for large gears

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Here's the end result -
P1020258 (Medium).JPG
(one of the new ones is on the left)

Michael

Originally Posted by Michael G

I like cutting gears and I find helicals even more interesting (takes all sorts).

There something just awesome about cutting gears and watching them almost magically mesh together. Like you did i really want to try a helical gear, i need to cut all the change gears for the D/H first though.
Is there any chance of a copy of your spread sheet?

Cheers,
Ew

Attached is my spreadsheet.
The first two tabs are just plate numbers for my rotary table and dividing (for non-differential dividing). I think it is correct but I rarely use it as I don't have a computer with me when dividing so I use the instructions that can be found on the web. I did this mainly so I could see whether I could generate plates to get other combinations.

The next two tabs are for spur gears. Input the DP or module required (blue box at the top) and the number of teeth the gears need to have (blue box on the LH side) and you will get the basics for blank size etc.

The last tab is for helical gears. Either put in the module or DP for the gear you desire in the top blue boxes and other details in the other blue boxes and it will give you the cutter to use, speed and other information you probably need.
Machinery's Handbook will give you the gearing you need based on a 10" lead machine. I have a 200mm lead machine, so the ratio down the bottom allows me to use MH to set up my gearing. It's very slack of me I know but I haven't bothered putting in all the ratio combinations so that it will automatically populate on the spreadsheet.

Note that you rarely get the exact gearing that you need (or have a cutter that is exactly the right DP/ module) but the errors involved seem to be small most of the time. If you wanted a spot on 100% exact helical gear you should probably be using a gear shaper or a hobbing machine.

Gearing.xls

Michael

I was talking to Simon about how I'd added a vernier scale to the SG and he asked where the picture was. Whoops - forgot to post it. Here it is. The original machine only had the zero marking on the LH side. I centred it up on the R/T and then scribed lines. The standard divisions are 360/50 = 7.2 degrees. The vernier scale being 1/10th has divisions of 7.92 degrees or 7 degrees 55 minute and 12 seconds.
To be visible I had to have 5 divisions up and 5 divisions down and if I ignored the 12 seconds on division 4 (5 is a whole number of divisions) the error for this round off is 4x12= 48 seconds. As a division is 7.2x3600 seconds, 48/25,920 = .00185 thou - that is 1.8 millionths of an inch down feed. Probably close enough.
P1020268 (Medium).JPG
(Actually I could have done better in retrospect because the R/T does have a seconds vernier scale although only to the nearest 10.)

Michael

Originally Posted by Michael G

I was talking to Simon about how I'd added a vernier scale to the SG and he asked where the picture was. Whoops - forgot to post it. Here it is. The original machine only had the zero marking on the LH side. I centred it up on the R/T and then scribed lines. The standard divisions are 360/50 = 7.2 degrees. The vernier scale being 1/10th has divisions of 7.92 degrees or 7 degrees 55 minute and 12 seconds.
To be visible I had to have 5 divisions up and 5 divisions down and if I ignored the 12 seconds on division 4 (5 is a whole number of divisions) the error for this round off is 4x12= 48 seconds. As a division is 7.2x3600 seconds, 48/25,920 = .00185 thou - that is 1.8 millionths of an inch down feed. Probably close enough.
P1020268 (Medium).JPG
(Actually I could have done better in retrospect because the R/T does have a seconds vernier scale although only to the nearest 10.)

Michael

Nice - I thought it a good idea when you first mentioned it. I may do the same myself one of these days.

Right now I'm just glad mine is working. I now have increased the ability of my shop to do fine work. Making a shim or similar precisely 1.73mm (for example) thick by parting off in the lathe was never possible for me, and using wet & dry or similar gave no guarantees of parallelism.

No longer a problem.

Next, the Hercus T&C grinder rebuild.

PDW

Hi Michael, I see what you mean now. The wheels on your SG are quite large and are perfect for such a modification. Very nice.

Simon

Depending on the state of the gears and screw it may be worth finding a micron or 10th indicator and mount it on the machine. The Blohm has provision for this, i'm sure it would be pretty easy to make a mount to suit.
Now you just need to sort out a "microtip" feed and you'll be set....

Whats the graduations? .001" i'm guessing, pretty course for a SG so the vernier scale is really a must. The vernier on the Blohm is 2/100ths of a thou, mircotip feed is 4/100ths. I tested the feed with a Millimess when i got it, just to be sure it was moving the amount it should have been.

Ew