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Cast Iron - Thin Sleeve Insert

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electrosteam

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I have a Spanish tool grinder, Premeta SL, a reasonable copy of a Deckel SO D-bit grinder.

The general condition is OK, but the sliding clamp fitting to the main horizontal shaft (Main Axle) is excessively worn.
A proposed correction requires boring out the original casting and fitting a sleeve.

The casting is 35 mm diameter at minimum, the axle is 24.99 mm diameter.
A sleeve of 1.5 mm wall thickness in extruded cast iron is suggested.

Does this sound doable ?

The sleeve needs a split for operation, but there are a couple of areas to be resolved.
The casting is only split for a part of its length, should the sleeve be split to match, or full length ?
Should the sleeve be glued into the casting ?

Stay well,
John.
 

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tornitore45

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1.5 mm wall is doable, is typical for cylinder lining.
Bronze may be suitable as well
I would slit the sleeve to duplicate the shape of the slit in the casting and place a pin in the hole at the end of the slit. The pin goes down into the sleeve slit and keeps it from moving in and out or rotating.
 

petertha

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Depending on the length, you might have more choices with sleeve stock & finishing the ID & OD to suite. Bronze is typically available like this, through suppliers or bearing shops. Possibly even alloy tubing, but bronze is well suited to this application. CI cylinder liners are machined ~ that wall thickness, but not before a big pile of swarf is generated.

 

SteveT

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If maching this sleeve in bronze how would you go about it?
I.D. or O.D. first?
If machining I.D. first would it be necessary to fit a removable liner inside to support the walls during machining of the O.D.?
Any help appreciated as I have to make some similar bering sleeves.
Regards,
Steve T
 

tornitore45

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I would bore for a slip fit on the ram. Then mount it on a mandrel ( a long bolt with two nuts machined conical to center the part) and turn the outside for a slide fit in the casting. Reduce the center 1/2 of the sleeve by 0.006 diameter to give room for the Loctite that glue the sleeve in the casting.
I would slit it after assembly to avoid the trouble of lining up the slit but it does not matter much even if the slits are not aligned it will work, actually it would keep the crud out.
 

goldstar31

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The odds of cast iron distorting by closing up after cutting are high. Perhaps making brass sleeves and using cotter pins may be the way to go. The new Mk3 Quorn is like that

Cheers

Norman
 

petertha

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I was visualizing pretty much what Mauro suggested. Hopefully the casting ID is in good shape (meaning within the gap limits of Loctite). Otherwise if it has to be line bored to true up that would be another setup.

Rob Renzetti on YouTube did an episode using Moglice (bedding epoxy) on his Chinese Deckel clone. Might be worth watching just for interest sake, but I would be reluctant to go down that path unless the slide post is mirror smooth & dimensionally accurate. The only reason I mention is possibly high grade epoxy could be used as the sleeve bonding medium to bridge larger/rougher gap.
 

electrosteam

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Thanks for all the responses.
I have finished the job:
- made up some setting aids and bored the casting out on the vertical mill,
- turned extruded CI to correct size for a glued fit to the casting (with 0.05 mm relieved centre),
- held piece in a large collet and bored out for fit to the shaft,
- inserted tight shim in casting gap, clamped casting closed and glued the sleeve in,
- made a plug to hold bore open and clamp to stop casting opening and slit sleeve to match casting,
- stock in lathe reduced to size of shaft,
- fitted clamp bolt to casting, held it on the lathe mandrel and faced both ends neatly,
- fitted to shaft and machine assembled for a test.

First effort was a 4-flute HSS ripper end mill.
The cutter then used to profile 400 mm 5 mm steel flatbar to make a spanner on CNC mill.
Bad burrs and generally less than stellar performance - but SUCCESS.

The sharpening process was full of mistakes and operator error.
Obvious that friction everywhere is high, so a strip down and clean is required.
Then, make some collets.

John
 

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electrosteam

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Finished the strip down and clean.
Had to use 2T press to separate the work spindle from its end bush.
Sheared the intermediate key into two parts, and caused some swelling of the end bush above its keyway.
Assembled with grubscrews in lieu of a key, really could do with re-making the end bush.
Lots of burrs etc cleaned off, several trivial modifications, lubrication and the unit now operates fine.
The photo shows the first 12mm cutter attempted.
Second Cutter 2 compr.JPG

Obvious I need to improve the centre gashing.
Looking at methods to allow cutters to 20 mm (and dream of 1").

Keep well,
John.
 

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