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[allan]

I'm new to this forum. Thank you for having me and thank you in advance for your help.  Background: While I was in school I purchased an old HP Grinder/polisher combo machine on cabinet (model 8CF) and it sat in a garage for several years before I finally decided it was time to learn the art of shaping stones on it following an equipment night at a local rock group.  Unfortunately, I wasn't able to find any user manuals for this particular model or even any close to it.  (If this post works correctly, there will be several pictures accompanying it). 

Current status: The machine turns on and runs.  It's fairly loud, but it seems to work okay.  I practiced shaping a stone on the far left wheel, which was the only one that had water properly flowing, and it seemed to work.  The other wheels were not aligned with the water inlets or were plugged, so I couldn't really test them very well.  I took apart the water assembly and cleaned it so the pump from the clean water bucket now works. I've ordered some penetrating oil to help since the water assembly was hard to disassemble. From left to right are the following wheels (I'm not 100% sure on the condition):

-8" Expando drum with some type of coarser grit belt on left end
-6" Crystalite 600 grit wheel (although it says 400 above it)
-6" Crystalite 600 grit wheel (although it says 400 above it)
-8" Expando drum with some type of finer grit belt
-8" Leather polishing wheel/pad on right end

I am wondering what I need to do to accomplish the following:  (If I need to post any of these in a different thread, please let me know).
1. how to disassemble so I can change/move the wheels
2. how to properly service it so it will run optimally, change out wheels more easily, and extend its life
3. is there room to add a third wheel in the middle section (if I add a corresponding water spout)
4. what recommendations for the wheels (I would like to have a general purpose setup for a variety of materials)
5. should I be doing anything else?

Again, thank you very much for your help!

[Slabbercabber]

That's a really nice machine.  A manual is pretty much out of the question on one that old but it's a simple thing to work with.  Start by thoroughly cleaning all the old rock scale off with a wire brush so things will slide on the shaft.  While you are working on that the entire shaft can be soaking in Kroil or whatever penetrant you have.  Remove the guards, remove the wheels on each end.  Those are held with set screws.  Remove the outer spacers.  Unbolt the pillow block bearings and lift out the shaft.  The pillow blocks will have setscrews on the shaft but may also have a collar that must be turned to unlock.  Now put a pipe over the shaft and against the shoulder of one of the bearings.  Start tapping the other end of the shaft with a soft hammer or block of wood.  Be gentle.  You don't want to upset the shaft metal.  With patience the bearings will eventually come off.  Make sure the bearings are free and quiet.  If not the bearing insert can be replaced.  You do not need to buy the entire pillow block.  The noise you hear is coming either from the bearings or the drive belt.  The aluminum housings are a great amplifier.  You can add another wheel in the center if you wish, but I wouldn't.  I suspect the wheels you have are mismarked.  They should be 100 and 400 more or less.  Try them on a rock and see how they work before you change anything.  The expandos give you all the versatility you need after the hard wheels.

[allan]

Thank you, Slabbercabber for all your help earlier!  I put this down for a while and came back to it.  I was hoping to follow up to learn some more, if you have time to help me finish the disassembly. 

I removed the shaft and a couple of wheels on the ends (1st pic).  However, I wasn't able to get past this point.  I've removed all the set screws, soaked all the points of contacts I could identify in Kroil.  I then tried dropping it against a block of wood on each end to dislodge the next pieces, without any success.  After cleaning the right end of the shaft (2nd pic) with 220 grit sandpaper, I tried a mallet to remove the piece, also without success.  A small spacer(?) came off on the left end (3rd pic), but I couldn't get the rest of it off.  (I apologize in advance, but I don't know the all proper names of the different parts, other than the bearings, pulley, and grinding wheels).  Any help you can provide is appreciated, including what tools you would use. 

Again, thanks!

[jakesrocks]

Beautiful machine. HP was the best ever built. Once you get it cleaned up & back in service, that thing will outlive you & your next generation.

Greatest penetrating oil of all is oil of wintergreen. Yes, that sounds weird, but it really is the best. Stand your shaft on end and put a few drops of oil of wintergreen on the shaft where it goes into the bearing. Let it sit over . Turn the shaft over & set it on a block of wood & start tapping the pillow block with a soft mallet. Be gentle, but don't be afraid to put a little force behind the taps. Use it on everything that needs to be removed. This is an old Navy trick for loosening frozen parts.

Word of warning. Oil of wintergreen burns like fire on bare skin. Don't get it in your eyes. It can blind you. Don't use it around pets. If they lick at it, it can destroy their liver.

[peruano]

Great machine.  I have the same one but I'm missing the original water trays for the expand wheel on the right.
There is certainly no reason not to replace the 6" wheels with 8" unless you do fine work that might need to get into tigher curves.  You may not need to replace the bearings, but you do need to remove at least one end to get the wheels off.  Yes you have room for three in the middle section.  I did the very thing to my machine - the cost is that there is a bit less space between wheels but it works.  I'd probably think about an 80 hard wheel, 220 or 280, and 600 novas for the middle and keep the expandos for flexibility and then buy 3m diamond belts for them.  You could go to 1200 with a nova by replacing the expand on one end, but its your call.  Sometimes a bit of steel wool action on the shaft will remove a glaze that is keeping  a bearing from sliding. I had to use a gear puller and adapted it for a real long reach to get one bearing to move along. I kept my original bearings and my machine is a bit noisy but I suspect its the metal housing as mentioned by slabbercabber.  Happy renovating.

[Slabbercabber]

Wow, wintergreen oil.  I had forgotten about that.  I don't think I've seen any in at least 30 years.  I don't know if it works better than Kroil, but it might be worth a try.  When I get really desperate I make a 50/50 mix atf and acetone.  That works fast but in this case I think it is just a matter of patience.  I'd love to see that setup with the gear puller.  That would absolutely be the best way to go.

[allan]

Thanks for all the advice, I really appreciate it. I was completely unable to remove much on my own, even after several rounds of soaking in Kroil, tapping with wood and a mallet. I ended up taking it to a machine shop to see if they had equipment to remove the parts. I'll find out this week if they were able to and repost later. I'll probably stick with 6" wheels in the center, but consider adding a 3rd. Any advice on best places to get a good value on 6" diamond wheels? Is the Nova the same thing as a hard wheel, peruano? Sorry for all the questions, I'm completely new at the lapidary aspect but hope to come to speed quickly.

[peruano]

Not the same.  A nova wheel has the diamond adhered to a firm rubberlike face.  Hard wheels are solid metal with diamond embedded in the surface.  Soft and hard wheels are available from most suppliers. JSGEMS.com is a good source of wheels that have helped me make decisions on wheels.  I know there are wheels like novas that are cheaper and reportedly of lesser quality.  The KingsleyNorth site has several options too. 

[melhill1659]

Hello, I too totally refurbished an antique HP E20 combo unit. From the water supply to the table it was mounted to. I've recently retired it for a Diamond Pacific Genie (actually 2) but still kept everything in hopes of using parts to make something else. Mine was made in the late 60's early 70's and it's so impressive the arbor, motor, pulley stuff still runs true!! Do you have yours up and running yet? I buy all my wheels from DP or the Rock Shed!! If you need detailed info The Cigar Box is excellent! Or you send it to them and they do it.
Mel


Sent from my iPhone using Tapatalk

[allan]

Back with an update. A machine shop was able to remove all but one pieces, but it's okay since it isn't one I need to move to run or make changes. I cleaned it real well with Emory cloth and lubed it with marine grease.
When you have a moment I have a couple follow up questions. It previously had 4 wheels and a lap on the end, but I'm going to add another wheel in the center, so 5 new 8" wheels: 80, 220 galaxy and 280, 600, 1200 nova wheels and a 3000 lap on the end (if I can figure it out).
My question is about the spot on the end of the machine for a flat lap. I'd like to do a magnetic lap with a 3000 grit, but don't know what might work. That end of the shaft is 3/4" in diameter and the existing back plate is aluminium so it won't work with any modern magnetic laps. Any recommendations?  (The magnetic nova lap back plates don't appear to be able to connect to the shaft because they have a 1/4"-20 bolt attachment.) If magneric doesn't work, are there other options for a 3000 grit lap that would connect (or could be used with my existimg aluminum back plate)? Thanks so much in advance!

[kent]

You could glue on a steel plate (disc) to your aluminum one. The aluminum is also thick enough you could drill and tap it for attaching a steel plate however I would consider adding a thin sheet of isolating material between the two. I use G-10 (a high pressure epoxy laminate) a lot in my shop which can be purchase from Mc Master Carr as thin as 1/32". https://www.mcmaster.com/#grade-g-10-garolite/=17leuyg


 

[allan]

Thank you for the suggestion, Kent.  Unfortunately, the 3/4" arbor hole in the aluminum goes completely through the aluminum plate, so tapping is not an option as far as I can tell.  With a domed aluminum plate, I'm not certain if I'd be able to glue on a steel plate properly?  If not, do you know of any other options?  I appreciate all your help. 

I was hoping to find a 8" flat lap with a 3/4" arbor hole somewhere online, but haven't had any luck yet.

... another thought, do you think a machine shop could drill and tap the arbor itself on this end sufficiently straight to use the ones I see currently in the diamond pacific catalog (to fit the 1/4"-20 bolt (like the Genie/Titan/Pixie and perhaps others))? 

[kent]

Hi Allan,

I also have a HP with an aluminum end plate for polishing however mine is flat so my suggestion was for working with a flat plate. Depending on how domed the disc is there are a variety of ways you could get it flat.
1. Turn it on a lathe.
2. Mount it on the HP shaft after removing the spray shield, turn it on and file/sand the plate smooth
3. Make a fairing piece that accommodates the dome, attach it to the plate, then the flat metal to it.
4. Wrap the outer edge of the disc with duct tape with the edge of the tape high enough to reach the center of the dome, mount the disc horizontal with a level, then mix up some epoxy with a filler to thicken (like cabosil), pour it in the "mold". After curing you'll have to fine tune sand to balance the disc.


I don't think I'd be comfortable with only a 1/4" bolt in the center of this sized disc.

#1 above is the best....#4 the worst....

[Slabbercabber]

Domed disks are rare and very expensive.  I would cover that one with padded leather and use it.  If you find one that would work other than thread size, it can be bushed with a reducing bushing or Keensert.  Check Mcmaster Carr.  If not, it is a simple two stage operation on a lathe and would be cheaper to make a new one than turn down the existing.

[allan]

Thank you very much for all the advice.  I ended up abandoning the search for a flat lap that would fit after learning that domed ones would be preferred for polishing cabs (vs. flat ones for the back sides or flat surfaces).  I am very new to this, so I apologize for my confusion.  I eventually found an adaptor to convert the 3/4" smooth arbor to the 1/4"-20 thread bolt so I can use the Standard Nova Disc, as well as polishing pads (felt, leather, etc.).  The disks are smaller (5.5" vs 8"), but I believe they should still work okay.  I also still have the original leather domed one, which has some foam padding under the leather.  Whomever had it before used some type of adhesive to attach the leather, and wrapped a wire around the edge.  Is this sufficient and safe?