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Conditioning Rings for a Flat Lap: Possible to Make Your Own?

#5 ii Alive!

Aluminum
Joined
May 12, 2018
Hi, All.

I just bought a used 12" Crane/Lapmaster machine for cheap. It came without the conditioning rings?

Would it make financial sense to make my own? I'm not a machinist per se, but this doesn't look particular difficult, and I have several machinist friends.

If you've done this, or know someone who does, I'm all ears.

Thanks,
#5

FYI/Full Disolosure: I've also posted "Wanting to Buy" in PM Classifieds. In case this is considered doubling posting, I'm flagging this post for a Mod to review.
 
I don't think there's anything magical about conditioning rings, it's more the way you use them that determines success or not. Diameters, material, height, weight, slotting on working face, cutting abrasive and concetration - all will play a role in the results and time to lap flatness.

To my understanding, some of the biggest issues are diameter and placement of the rings relative to lap plate. The amount of overhang inboard or outboard helps set flatness or concave/convex error.

I'm not an expert, hopefully others will chime in.
 
Like milland said above- nothing special at all about the rings. Probably need to be cast iron, not steel. Just be sure to know what size the original ones were, thickness and height as well as O.D.. simple lathe work, they will lap themselves to the table so dont try to be super accurate making them.
 
We have a 12" Lapmaster at work, but I built a small one for home. You can probably find cast plumbing fittings at a good hardware store. Face the end and Bob's your uncle. Note that the factory ones are pretty heavy and slotted; getting those is best if you can afford it. Make sure you rig up an indicator bar so you can monitor the lapping plate flatness. It takes very little time to make it go convex, but near-to-forever to correct the problem. So long, in fact, that it's easier to just send it out and have it surface ground.
 
We have a 12" Lapmaster at work, but I built a small one for home. You can probably find cast plumbing fittings at a good hardware store. Face the end and Bob's your uncle. Note that the factory ones are pretty heavy and slotted; getting those is best if you can afford it. Make sure you rig up an indicator bar so you can monitor the lapping plate flatness. It takes very little time to make it go convex, but near-to-forever to correct the problem. So long, in fact, that it's easier to just send it out and have it surface ground.

Thanks to all of you for your answers.

Conrad, thanks for your response. A very knowledgeable buddy of mine has spec'd out the inner and outer diameters of the factory rings that go to this machine. I'm going to contact him, then will post those numbers over the weekend. I'd like to compare those with the dimensions of your own rings and/or the factory rings.

I should also mention, folks, that I'm lapping industrial plastics on this machine, like Delrin or Ultem, and likely will never lap metal. In light of this, I'm thinking the rings I use can be lighter that the factory spec ones -- for instance, maybe the corrent outer diameter, but with a thinner wall to the pipe, and perhaps also not as tall. If the piping is cheap enough, that will allow me to experiment.

Thanks again, Everyone. Very Helpful.

#5
 
The rings serve multiple purposes. One is to hold the parts, another is to keep the table flat. This is done by moving them in or out on the table. If you get to light on the rings they may not do a good job at keeping the table flat and conditioned. Something to do some homework on...
Is your machine a cast iron table?
 
The rings serve multiple purposes. One is to hold the parts, another is to keep the table flat. This is done by moving them in or out on the table. If you get to light on the rings they may not do a good job at keeping the table flat and conditioned. Something to do some homework on...
Is your machine a cast iron table?

Rob, thanks for pointing this out. I confess my ignorance and this will be a learning curve, like almost everything else I've had to do for my business. But I LOVE learning, so it's not a chore.

I make high-end guitar picks, and the biggest challenge is I make most of them from a material called casein plastic. It hates everything -- water, heat, sanding, tumbling. It's just impossible stuff. I've analyzed the finished products of several major competitors and can tell by inspection that they are definitely lapped. So I'll learn as I go.

I just got the machine and am excited about learning this new skill. Thanks again, Rob.

5a5HD09.jpg
 
I don't know anything about lapping plastics, but I can imagine the grit will embed in the plastic and mostly lap the plate into a shape you don't want. The rings are what fix that, if they can keep up with it. Do you have the manual? I scanned one and put it here- Library Items

I notice you don't have the pump and are missing one of the ring bearing thingies. You might consider (if you already haven't) using adhesive lapping films on the plate, rather than slurry. That would seem better for plastics. No heavy rings needed (I think). These people know near everything; you might want to give them a call- Lapping / Polishing Abrasives - AdvancedAbrasives.com
 
I don't know anything about lapping plastics, but I can imagine the grit will embed in the plastic and mostly lap the plate into a shape you don't want. The rings are what fix that, if they can keep up with it. Do you have the manual? I scanned one and put it here- Library Items

I notice you don't have the pump and are missing one of the ring bearing thingies. You might consider (if you already haven't) using adhesive lapping films on the plate, rather than slurry. That would seem better for plastics. No heavy rings needed (I think). These people know near everything; you might want to give them a call- Lapping / Polishing Abrasives - AdvancedAbrasives.com

Conrad, really appreciate the links and advice. I'm a sponge for new info and truly love learning.

Just an FYI that I've inspected closely the products of two or three of my major competitors, and all them appear to be lapping in their final stages. You can see the tiny streaks across the surface of the plastic.

Thanks Again. Truly grateful.

All the Best,
#5
 
I know zero about guitar picks, but suppose that you are after a nice finish, not flatness measured in wavelengths of light. So it probably won't matter to you if the plate goes somewhat convex or concave. The tolerances that people in this forum are talking about are appropriate for high-end measuring equipment, not for a guitar pick. I suspect it will take a long time for the plate to become convex or concave enough to matter to you.
 
I know zero about guitar picks, but suppose that you are after a nice finish, not flatness measured in wavelengths of light. So it probably won't matter to you if the plate goes somewhat convex or concave. The tolerances that people in this forum are talking about are appropriate for high-end measuring equipment, not for a guitar pick. I suspect it will take a long time for the plate to become convex or concave enough to matter to you.

Well, true, but IMO there's the matter of pride and principle. Besides, one might want to lap a piece of metal flat at some point in the future and correcting a lapping plate that's more than a few thou out is a nightmare. It's way easier to keep it flat through proper adjustment right from the beginning.
 
Conrad, really appreciate the links and advice. I'm a sponge for new info and truly love learning.

Just an FYI that I've inspected closely the products of two or three of my major competitors, and all them appear to be lapping in their final stages. You can see the tiny streaks across the surface of the plastic.

Thanks Again. Truly grateful.

All the Best,
#5
The streaks could be from an embedded grit lap or graded lapping film. 3M lapping film is fantastic, for guitar picks should work _great_. I imagine you'd get a very long life out aluminum oxide, but if you're really keen to get fancy they have diamond too. Could be a marketing plus haha.
 
I know zero about guitar picks, but suppose that you are after a nice finish, not flatness measured in wavelengths of light. So it probably won't matter to you if the plate goes somewhat convex or concave. The tolerances that people in this forum are talking about are appropriate for high-end measuring equipment, not for a guitar pick. I suspect it will take a long time for the plate to become convex or concave enough to matter to you.

Thanks to everyone for the continued discussion, and for your patience in teaching me about something I need to learn. The sooner I get this machine figured out, the better I can grow my business.

I do like the idea of flatness, but yes, we're not talking mil-spec tolerances here.

My first goal with the machine is mainly to do just the final lap or polish finish, so I would not be using aggressive grits at the outset. I'm talking a slurry with grit ratings of roughly 25,000-100,000, where the abrasive particles range from about 1 micron to .25 micron. Once I figure out that process, that I will back it out and begin to experimewnt with more aggressive grits. But I'd be a happy camper just solving the final piece of the puzzle.

BTW, I read somewhere a while back that some people use regular old Corian as the bottom plate in lapping. Would that be a low-cost option for me?

Thanks,
#5
 
Well, true, but IMO there's the matter of pride and principle. Besides, one might want to lap a piece of metal flat at some point in the future and correcting a lapping plate that's more than a few thou out is a nightmare. It's way easier to keep it flat through proper adjustment right from the beginning.

Conrad, I'm really into exactitude and so I'm all in favor of getting this machine lapping as flatly as possible. However, because I'm a tiny business trying to solve a polishing problem as opposed to a flattening problem, if that costs a lot of extra money I'd just soon let it ride and come back to it when I have more money in the bank.

BTW, I ask the gent above, have you heard of people using a lapping plate made of Corian?

Thanks,
#5
 
The streaks could be from an embedded grit lap or graded lapping film. 3M lapping film is fantastic, for guitar picks should work _great_. I imagine you'd get a very long life out aluminum oxide, but if you're really keen to get fancy they have diamond too. Could be a marketing plus haha.

Screw, thanks. Interesting.

Something I forgot to mention. The main material I use hates water and the work piece will warp in a few minutes of exposure. I assume, then, that lapping with oil is not a problem, correct? Again, this is all new to me.

Thanks,
#5
 
I would think corian could work, it might not last long though. If you did then you probably dont want to use "rings", just make a carrier that is the same dia as the rings and mill shallow guitar pic sized pockets in the end. This would hold more pics since the carrier does not have to fit inside the rings.

Many polishing machines use a pad on a granite or ceramic table. That is polishing, not "real" lapping though.

A granite (or corian) table would probably be fine for what you need, even a round piece of countertop. Stick a pad on it and go. Granite is probably more stable, but may not matter for your application.
 
For plastic parts, Use pads ,don't mess with the cast iron lapping plate surface. Just get it flat first, then glue on a pad. Pad replacement when it becomes worn is simple, and you are good to go again. The cast iron NEVER looses shape.

Make your rings , carriers, conditioning ring or bruiser out of what ever you want, pipe or plate . Glue on wear buttons with epoxy uniformly around the perimeter.. Make the wear buttons out of the same (or similar) material to the work.

If you change work, Change wear buttons to suit.

Work carriers can certainly be made From Corian. plexiglass works, so does G10 and micarta. Heck, formica works.
The carriers need to be thinner than the work so the weight and pad can press on the workpieces.

Lapmasters plates are never flat. they are constantly going from convex to concave or vice versa, depending on skill of the operator. The idea is to limit the excursions ;-)
 
Is it possible I can shortcut this process, and avoid the condition rings entirely, at least for now?

In other words:

1) I created a flat jig to hold the picks in place
2) I prepare a 12-inch disc with, say, a 1.0 micron film attached, then lower that onto the work pieces.

Excuse my ignorance. Would this work, at least as a test?

Thank You.
 
I would try a "jig" (carrier) that is the size of the OD of the iron ring. This is a round part maybe 4" or so in dia that has pockets in it for as many pics as you can nest on one end.
To test it just use double sidded tape to stick the pics to the right sized round stock. It just needs to be tall enough to get to the ring rollers. If it is to light to give good downforce you can set a heavy weight on it. Once you know how much weight is best then make the carrier weigh that much, steel, plastic or aluminum vary the length as needed... These carriers will slowly spin around in the bearings on the arms to give you the nice lapped looking finish. One big jig or carrier will not auto rotate on the table and you will end up with straight lines in the parts and not as flat either (but probably flat enough).
A large tuna can filled with resin or epoxy could be close to the right size to test with.
 








 
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