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Lapping Machines

dstryr

Diamond
Joined
Jan 22, 2010
Location
Nampa Idaho
Thinking about moving out of California and would no longer have access to a friends lapping services.
Parts I'm working on that need lapping to support machining are 30" Diameter x 4-8" tall. When they are lapped they are not finished on the OD so not worried about slight scratches from the pods...


Can anyone recommend a larger machine with an estimated cost ?
 
I've only used one and that was a Lapmaster. Dead simple model. Bought used for <$1k IIRC. Not as big as you will need though. It had 3x 12" pods. I think finding one as big as you will need will be few and far between and correspondingly more expensive.
 
What sort of flatness/parallelism/surface finish do you need? What material?

Given that buying something the size you need may be $$$$$, what would a scheduled shipping cost? If you do enough maybe it could be cost effective?

Or, set up a Bridgeport with a massive fly cutter, but you might wind up with a somewhat aspheric surface... :D

More seriously, could a specialized lathe get you the needed geometry?
 
I have a 36" table Spitfire (now Speedfam) lapping machine. To lap a 30" part, I think you'd need a 84" table machine like this:

Lapmaster Wolters Model 84

That's a big machine weighing in at around 20k lbs. I don't know anything about the cost of new lappers, but I'm sure it's not cheap. That table alone has got to cost an arm and a leg. I'd hate to have to replace it.

Any chance you can Blanchard grind your part? You can get away with a much smaller machine in that case.

What is your friend using now?

If you have to lap them, and you'd consider a used machine, I can put you in touch with a guy who goes by the name of lapperking who deals in used lappers. It might be at least worth talking to him about what your application.
 
CEBA TECH Inc
13213 NE Kerr Road #110
Vancouver, WA 98682
360-891-1823 shop

These guys are lapping machine gurus. They sell consumables and deal in used machines. Good people.
 
Parts are aluminum (7075) and Im currently having them lapped to flat within .001. They are super thin diameter and easily twisted when the bottom face isn't perfectly flat. I can mess with shims in a pinch but its not feasible for production / having an employee do it.

Il check out some of these resources post.
To give an idea... wall thickness is around .300" and final part has round ness call outs like .005 over 28"
I'm not sure there is an easy way to hold the part on a grinder without distorting it.
 
Parts are aluminum (7075) and Im currently having them lapped to flat within .001. They are super thin diameter and easily twisted when the bottom face isn't perfectly flat. I can mess with shims in a pinch but its not feasible for production / having an employee do it.

Il check out some of these resources post.
To give an idea... wall thickness is around .300" and final part has round ness call outs like .005 over 28"
I'm not sure there is an easy way to hold the part on a grinder without distorting it.

Build some cases and ship the parts to the person currently doing them. While not ideal, neither is buying a specialty very large lapping machine. The cases can be reused over and over again. Probably have to have more parts in WHIP but trying to teach a new company to do something you already have a good solution is seems tougher.
 
Parts are aluminum (7075) and Im currently having them lapped to flat within .001. They are super thin diameter and easily twisted when the bottom face isn't perfectly flat. I can mess with shims in a pinch but its not feasible for production / having an employee do it.

Il check out some of these resources post.
To give an idea... wall thickness is around .300" and final part has round ness call outs like .005 over 28"
I'm not sure there is an easy way to hold the part on a grinder without distorting it.

Holding your part on a grinder might not be that difficult. You could probably get away with setting it on the table and blocking it up with chunks of steel to keep it from sliding around. Being aluminum could actually help for flatness because the magnetic chuck wouldn't be drawing the part down and distorting it. It could sit in it's relaxed state while you just kiss the top enough to get it flat. If you're worried about the ring spinning, you could put a Mitee Bite to grip it in one place. The chucks on Blanchards have tapped holes for mounting things to- at least mine does. I've never ground aluminum on mine, so I can't say for sure that it would work, but it seems like it should with some experimenting.

Check out this video that NYC CNC did touring a Blanchard grinding shop. There are some good insights in there.

Bourdelais Grinding Shop Tour! Blanchard and Double Disc Grinding! - YouTube


It seems like the better option to me and what I would at least seriously look into. A lapper for that size part is huge, rare, and expensive. Meanwhile, the Blanchard is the opposite of all those things. Plus we find that the Blanchard is more useful/versatile for other applications around the shop. It seems like we're always grinding fixture plates, dies, or something other than what we initially purchased it for.
 
Do you know what machinery is being used now to produce the present results? (I assume acceptable results)

With a part that "flimsy:. the process could be no more than a rubbing table with attention to surface wear.

Simple rotation of the lap, with hand guided motion of the part.

Some fine optics have been produced with just that method.
 
What are you finish machining them on?

I'm thinking facing on a VTL. Vacuum hold down on 3 pods for height control. Multiple other pods in between that float vertically, and can be locked with a split clamp, if there's a chatter problem.

But qty required might point towards the reusable shipping cases already suggested. Experience suggests you'll need to 'fix' them on occasion.
 
Will not recommend a machine or talk about the learning curve.
More to ask why "no longer have access to a friends lapping services".
Can not ship parts to your friend? Big parts yes but they will need a big machine (read real money).
Interested to know what your friend has. Are these 3 foot rings or 3 foot dia. full surface parts.
Bob
 
What are you finish machining them on?

I'm thinking facing on a VTL. Vacuum hold down on 3 pods for height control. Multiple other pods in between that float vertically, and can be locked with a split clamp, if there's a chatter problem.

But qty required might point towards the reusable shipping cases already suggested. Experience suggests you'll need to 'fix' them on occasion.

Ive thought about using a VTL as well or maybe springing for a new Grob with Turning integrated.
I can get it right with milling but it takes way too much care with indicators and shims on every part
'
 
Will not recommend a machine or talk about the learning curve.
More to ask why "no longer have access to a friends lapping services".
Can not ship parts to your friend? Big parts yes but they will need a big machine (read real money).
Interested to know what your friend has. Are these 3 foot rings or 3 foot dia. full surface parts.
Bob

Ill find out from him tomorrow what kind of machine he has in their shop.
Parts are about 30" OD with 25" ID face
Wall thickness is about .250 thick on the finished part but I leave some holding tabs on the ID and really small surface area for to make it easier for lapping.

Worried about lead time back and forth. Shipping 3-4 days each way and sometimes they get lapped twice depending on the material stability
 
In your first post you said that they were 4-8" tall.

Then .25 - .300 thick.

???


----------------------

I am Ox and I approve this h'yah post!
 
In your first post you said that they were 4-8" tall.

Then .25 - .300 thick.

???


----------------------

I am Ox and I approve this h'yah post!

Majority of the Wall thickness .... .250 -.300 on 28" diameter...
Couple parts have a flange on top / bottom.
 
I have a 36" table Spitfire (now Speedfam) lapping machine. To lap a 30" part, I think you'd need a 84" table machine like this:

Lapmaster Wolters Model 84

Ask and ye shall receive ...

Two Spade Machinery LLC - Speedfam SPEEDLAP 84 BAW

No idea what the price is but these guys have been not too outrageous on a few other things ... while we're here, what the hey :

SpeedfamSPEEDLAP84BAW-1.jpg
 








 
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