Harrison Horizontal/Vertical Mill Restoration

[Hopefuldave]

I have been thinking about the motor today. One of the things that crossed my mind was the fact that it doesn't have an external fan.

Given that I'm going to run it from a VFD, I'm just wondering if there will be sufficient throughput of cooling air at lower speeds. I will still be using the gearbox so it won't be running that slowly. Maybe a solution will be to install a separate external fan (like a large computer fan). I don't really want to modify the motor to fit a fan directly to the output shaft.

That was my worry when I put the VFD on my Holbrook, I took the last couple of inches from a chemical drum as an adaptor and fitted a hefty fan, used a programmable relay output on the VFD to switch it OFF over a certain output frequency (35 Hz) so it stays on and cools the motor between uses (and reminds me to switch off at the end of the jobs). I'll post a pic later!

Dave H. (the other one)

 

[Carl Wilson]

That is a very good idea. I was wondering how to trigger such a fan, thinking I might have to embed a thermistor into the stator and couple that to a VFD analogue input.

Programming an output relay to switch the fan on within a certain frequency range, ie those values when a fan would be needed, is an excellent workaround.

 

[Carl Wilson]

The motor rebuild is complete, with the junction box parts cleaned and assembled. The pulley has also been refitted.

Now to carry on with the restoration. I think the next thing to be removed will be the table assembly complete. I can then take off the Brook Gryphon feed motor and get that converted to delta.

 

[Carl Wilson]

Hugh this is for you.

Here is the interior of the column showing the entry point of the feed control cable conduit.

To gain access to this point it is necessary to remove the fibre glass belt cover. One is then confronted by a panel secured by two screws, in this position.

The cables from the conduit are connected to cables coming from the main contactor and control panel via a group of terminals on the back of this panel.

Then these cables run to the main contactor and control panel through this hole in the stand.

 

[HughF]

The motor rebuild is complete, with the junction box parts cleaned and assembled. The pulley has also been refitted.

View attachment 186816

Now to carry on with the restoration. I think the next thing to be removed will be the table assembly complete. I can then take off the Brook Gryphon feed motor and get that converted to delta.

You should be able to convert the table feed motor to Delta just with a simple rewire inside the terminal box. The instructions were printed on the inside of the terminal box on mine.

I have bypassed the direction reverse switch in the table box, I'm using that to drive the vfd direction inputs. I've jumpered the three phase wires that come up from the base directly to the phase wires that head off to the feed motor with wago connectors so it's a straight path down to the bottom.

I also had a 415 out vfd on the shelf so didn't need to touch the spindle motor.

Do you have the full horizontal setup for yours too? Takes a while to change over but gives you options.

 

[HughF]

Hugh this is for you.

Here is the interior of the column showing the entry point of the feed control cable conduit.

View attachment 186817

To gain access to this point it is necessary to remove the fibre glass belt cover. One is then confronted by a panel secured by two screws, in this position.

View attachment 186818

The cables from the conduit are connected to cables coming from the main contactor and control panel via a group of terminals on the back of this panel.

View attachment 186819

Then these cables run to the main contactor and control panel through this hole in the stand.

View attachment 186820

Thanks very much Carl, that's very helpful. I think If I pull my machine out from the wall a bit I can get round the back and access this cover.

 

[Carl Wilson]

No problem Hugh. My Gryphon motor doesn't have an external junction box. Rather it has three conductors coming out from the star connected stator.

These ran through conduit into the feed control box, before I removed all of that.

 

[HughF]

No problem Hugh. My Gryphon motor doesn't have an external junction box. Rather it has three conductors coming out from the star connected stator.

These ran through conduit into the feed control box, before I removed all of that.

Ah, that's unfortunate. Judging by your earlier pictures in this thread, I think mine is quite a bit later than yours. Have you run yours up since acquiring it? They are very good machines, very soiid.

 

[Carl Wilson]

Hi Hugh. I've not run it up since getting it. I'm looking forward to that day. Yes, I have the horizontal set up too. I got a lot of tooling when I bought it as well.

Here is my Gryphon motor.

You are right about my mill being an earlier version. I think it dates from the late 1960's.

 

[HughF]

Ah, that's interesting.... Mine has a vertical motor on the left hand side of the table.

Photo of mine on collection day:



And here is a picture of the 4kW VFD stuffed in the bottom cabinet.

 

[Carl Wilson]

Hi Hugh, great pictures, thanks for sharing. Mine had two delivery days, and the first is one I'd rather forget!

It looks like yours might be the universal model, where the table can also be rotated. Like this illustration in the manual.

You can read about what happened to my mill on delivery in my original thread, entitled "Ebay-tastic". It is too painful a memory for me to re-live here!

 

[HughF]

Mine is indeed the universal model. I've just found your original thread... Bad times indeed.

I need to get a manual for mine...

 

[Carl Wilson]

They are available on eBay. If you like though, pm me your address and I will copy mine and send it to you.

I should really scan it and put it into pdf format, but I never seem to get around to doing things like that.

Your mill also has the clutch. Mine has not. I hope one day to find or make the parts for that and retro fit.

I'm told that these machines use all the same mechanics as the Harrison L5 lathe.

 

[Carl Wilson]

This evening I removed the complete table assembly. First of all took off the Y axis clamps, being careful to ensure each gib remained with it's respective clamp.

I rigged the table and lifted it off. This was quite an awkward job, since the crane didn't fit in very well and there isn't much room to manoeuvre.

Sharp eyed readers will notice that the securing bolt in the sliding portion of the crane jib is not fitted - don't worry. This was just during the set up. The bolt was in for the actual lift.

The table came off relatively easily. I lowered it onto my portable welding bench.

Everything is very dirty due to years of neglect coupled with well meaning, but ultimately wrong, greasing.

I got my first glimpse of the knee mechanism. It is full of what appears to be an unholy mixture of swarf, congealed grease and general detritus.

Believe it or not, that is meant to be a skew gear!

The next job will be to strip the table, starting with removing the X axis lead screw and feed gearbox/motor assembly. There will then be a lot of cleaning, which I'm sure will reveal further issues requiring attention. The ways seem to be in decent condition, just very greasy and dirty. I'm hoping that there isn't any scoring. Of course the worry is the grease and dirt has had a grinding paste type action.

The eventual reassembly to the machine should be less troublesome as it can be done piece by piece.

 

[Carl Wilson]

Here is the Y axis lead screw nut, and a view of the table ways. The protective strip got bent during removal. Add that to the list of parts I have to make!

 

[Carl Wilson]

Commenced the strip down of the table assembly today. I started by removing the X axis lead screw and the feed gearbox complete with motor.

The leadscrew was a straightforward task. Completley removed the left hand bearing keep by taking off the bearing end cover and removing the 3/8 UNC nut from the end of the leadscrew. Then unscrewed the four 1/4 UNC cap screws securing the keep casting and withdrew it. The casting is located by dowel pins. Two SKF thrust bearings were collected from the leadscrew.

Then the right hand keep was unscrewed. Rotating the X axis feed hand wheel then brought the leadscrew right out of the nut in the gearbox.

With the leadscrew gone, the feed gearbox could be removed. This picture shows a good view of the leadscrew nut within the gearbox. The nut has a worm wheel that is driven by a worm on the topmost external shaft. Locking the screw and rotating the nut moves the nut and by extension the table along the screw. Rotate the screw and lock the nut (achieved by the worm and wheel) and the table traverses man-draulically.

Removing the gearbox entailed taking out four 1/4 UNC securing bolts. Two can be seen above the nut in the photo.

The second two are underneath the table. This bracket also features a locating dowel. A few sharp taps with the Thor hammer and the motor/gearbox was off.

Here are some views of the interior. When I drained the oil, two things were apparent. There wasn't much of it and what there was had rather a lot of brass/bronze debris in it. More of that inside. The worm wheel on the nut seems a likely source of this.

My Brother restores bikes. He told me the orange paint inside the gearbox is to seal.any casting porosities against the oil. Apparently Royal Enfield did the same.

To remove the motor, it is necessary to take out three 1/4 UNC cap screws. In this picture the position of one can be seen on the motor. The Allen key gives away the second, with the third just above, next to the sight glass.

With the bolts out it just remained to take the drive pinion off the motor shaft. An M4 cap screw retains this, a key providing the driving feature.

The retaining screw is quite awkward in terms of access. After cracking the screw in with the correct tool, I then had to resort to long nose pliers to gain any purchase.

This is the stage I left things at. I think I'm going to have to use a sort of slide hammer action to pull off the pinion and free the motor.

 

[Carl Wilson]

I am back at work now so there will be no more practical updates for a few weeks.

In my last stint in the workshop I succeeded in removing the Gryphon motor from the feed gearbox and made some good progress in dismantling the box itself.

Before I go any further, I will post a picture from the parts drawings of the gearbox. This should make the description easier to follow (and write!) as reference can be made to the numbered parts shown in the drawing.

In the last post you'll remember I was trying to remove the Gryphon motor, having taken out all of the securing bolts. I initially thought I'd have to remove the pinion to get the motor shaft through the gearbox bore.

That wasn't necessary. On the motor shaft are a lip seal and a spacer, items 12 and 13 on the drawing. Overcoming the fit between the OD of the seal and the gearbox bore saw the motor out.

I then used one of my budget Silverline pullers to get the pinion off the motor shaft.

The motor shaft has a flat rather than a keyway. The key does engage a keyway in the pinion. I also noticed at this point that the front motor shaft oil (or rather grease) seal is damaged.

Here is the pinion, item 9, with it's key, item 10. The key has a locating spigot that engages a hole in the pinion boss.

I now put the motor to one side. I will be rewiring the stator to delta, as well as replacing the bearings and seals. For now though I turned my attention back to the gearbox.

Before I treat the dismantling of the box any further, it is worth making a few comments on it's design and operation. I suspect an arbor press was used in its assembly as there are a lot of press fits.

Deep groove ball bearings are used throughout with large ones on the worm wheel/leadscrew assembly, item 14. The gearbox took me back to my time working on British aircraft of a certain vintage. It had the feel of something like a trim drive gearbox.

When power feed is wanted, the leadscrew is dogged to it's bearing keep by operating a mechanism in the handwheel. The leadscrew is then unable to rotate. Thus as the motor rotates the worm to drive the leadscrew nut via the worm wheel, the gearbox and hence the table to which it is attached traverse linearly along the leadscrew. The large deep groove bearings, items 15, take the end thrust caused by the worm drive and cutting forces.

Manual feed is achieved by unlocking the leadscrew. Turning the handle then traverses the nut, which is locked by the worm and wheel, thus moving the table to and fro.

It is immediately apparent from the drawing that the worm drive shaft, item 19, must be withdrawn with the worm before the leadscrew nut can be pushed out.

So in preparation for this and further dismantling I first removed the LH and RH worm drive shaft and drive gear shaft locating plates, items 21, 25, 29 and 34 respectively. These were all held in by three 4-40 UNC countersunk bolts, some of which were a bit obstinate.

Removing the locating plates revealed the bearings. Here is the face of the RH worm shaft bearing, showing the bearing and locating circlip, items 23 and 24. Incidentally the bearing races underneath the gearbox in the following picture are nothing to do with the mechanism; they are salvaged ones that I use as packers in pulling or pushing arrangements. I sometimes also use them as parallels.

I removed the circlip and then drove the bearing out, still attached to the shaft, using a brass drift on the LH side shaft face. Having done this it was then possible to take off the bearing. Silverline puller earning it's wages again.

With the RH bearing off the shaft there was enough clearance to drive the complete assembly out through the LH side.

The worm gear is driven by a spline on the shaft as indicated on the drawing.

With the worm gear assembly out, the leadscrew nut complete with worm wheel could be removed. I first took off the locating plate, item 16. This was secured with four 4-40 UNC screws. Next I removed the locating sleeve, item 17. This is locked in position by a dog point 1/4 UNC grub screw that engages with a circumferential groove in the sleeve.

The locating sleeve has two 4-40 UNC tapped holes in its outer end. I put two screws in these to secure a toolmakers clamp in place. This gave me a surface to push against to allow extraction of the sleeve.

I've now reached the maximum upload limit for one post. I will continue the description of the gearbox strip down in the next one.

 

[Carl Wilson]

With the toolmakers clamp in position I was able to drive out the sleeve with a drift.

In the bottom LH corner of the above picture you can see the top most 1/4 UNC motor mounting bolt. This passes through the circumferential groove in the sleeve, though does not engage with it. I'll have to remember to position this first prior to re-assembly.

With the sleeve and locating plate off I then pulled out the complete leadscrew nut, worm wheel and bearing assembly. I did this using an ad hoc arrangement made up from my machine clamping kit. Unfortunately I did not take a photo of this.

While I was pulling out the leadscrew nut assembly, the cage of one of the deep groove ball bearings, item 15 in the drawing shown previously, disintegrated. No matter as I will be replacing all of the bearings.

Here is the leadscrew nut assembly removed. The inner race of the disintegrated bearing is still fitted. The threads in the nut are good and it is a decent fit on the leadscrew.

Here is a bonus photo that should have been in the initial dismantling post. It shows the lip seal and spacer on the shaft of the Gryphon motor, before I removed them to pull off the pinion. The new ones will have to be pre-assembled to the shaft before the pinion goes back on.

The next task will be to take out the drive gear assembly. This will be done in a substantially similar way to the worm shaft removal.

Then it will be a case of cleaning and inspecting everything for wear or damage. All bearings and seals will be replaced. The gearbox casting will be stripped and re-painted. I can't wait to see the back of the daubed on silver hammerite.

In retrospect I probably should have dunked the gearbox in equipment cleaner before starting the strip. It is liberally covered in oil, grease and congealed swarf. This made a fairly dirty job even dirtier. Not to worry.

I am hoping these posts, and indeed the whole thread, will prove to be useful to others. I could not find any information at all on stripping one of these gearboxes on the net. So I will be very pleased if I have added to the sum of accumulated knowledge.

 

[scottmk1]

The red paint inside the castings is to seal them, used to see it in various marine gearboxes and older crank cases. More modern engines don't seem to have it though - Glyptal is the name of the stuff and last I looked it was quite expensive.

 

[Carl Wilson]

Hi Scott thanks for confirming that about the paint, and providing it's name! Thanks for reading my thread. I'm enjoying yours on your lathe.

I've decided I'm going to include an image of a relevant drawing from the machine manual in my posts detailing work on sections of the mill.

That way, anyone that has one of these machines but doesn't have a manual should find this thread a good reference.