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Smokedaddy
02-04-2010, 09:45 PM
Take a look at the picture and notice the "sleeve" that the arrow is pointing to. This thing is about 8-inches long and is supposed to be a slip-fit over the counterweight shaft. You can't see them in this picture, but there are 8 tapped holes in the sleeve, which are divided into two rows 4 holes each, 90 degrees apart radially, with the center line of the holes running parallel to the long axis of the sleeve/dec shaft.

'm trying to disassemble the mount, and I'm having a devil of a time doing it. This sleeve will NOT budge. I have let the mount set for a couple of nights with the DEC shaft pointing nearly vertical, and sprayed some WD-40 on the DEC shaft where it enters the sleeve. This afternoon I tried heating the sleeve with a propane torch and then attempted to tap it off the DEC shaft with a hammer hitting a 2 x 4 up against a bolt that I inserted into one of the tapped holes. In other words, I'm trying to get the sleeve to move towards the counterweight threads.

Damn thing didn't budge at all! Do you think the propane torch is getting the sleeve hot enough? The sleeve looks to be about a 1/4" thick. I'm out of oxy/acetylene fuel, but perhaps I should get my bottles refilled and try again.

http://www.pbase.com/smokedaddy/image/121686104

Thoughts?

JoeFin
02-04-2010, 09:53 PM
I know Aluminum to Steel can be broken free by heating with propane torch and then immediately cooling it with WD-40

Yankee1
02-05-2010, 12:28 AM
The inside shaft must be kept cold when heating the outside sleeve.
Heat can enter those holes and cause the sleeve to lock up. If this happens you must cool down the whole thing and start over.
Protect the inside shaft from the heat and as you heat the sleeve test it very frequently by trying to twist and pull it off. If you wait too long to test for it being loose the heat will sink through the sleeve into the inner shaft and cause it to expand and lock up tighter. Hope there are no burrs at the bottom of those tapped holes.

lwbates
02-05-2010, 12:31 AM
Don't use the driving against the bolt with a piece of wood trick, as this distorts the sleeve, tightening it against the shaft just forward of the bolt, in the direction you're trying to move it. If the threaded holes are the only place that you can apply force, use the shortest bolt you can in the hole, so that you can use a brass drift against the bolt head while it's tight against the sleeve. Using oxy-acelylene with a large tip, heat the sleeve as hot and fast and evenly as you can. If it won't break loose quickly, the shaft will absorb to much heat and expand also. If the first try fails, spray it liberaly with Break Free or another top quality penetrating oil and let it cool to room temp. before trying it all over again. If all else fails, you could try heating it and then quenching in cold water to shock the corrosion in the fit.

If you don't mind losing the sleeve, you can carefully split it in a line up one side with a narrow slitting wheel on a grinder. You then have to grind the part in the corner that you couldn't reach with the slitting wheel. This of course will leave a linear scar down the shaft on one side, but since it's not a running fit, it's cosmetic only.

If you can get the assembly into a milling machine, you can use an end mill to machine a full length keyway down one or more sides of the sleeve, stopping just short of cutting through the sleeve wall. This will relieve the fit enough to slide it apart.

The Artful Bodger
02-05-2010, 02:44 AM
Hmmmmm... if the assembly was heated then dunked in water the outer sleeve would cool first and become slightly stretched? Maybe after a few cycles it would be loose.:rolleyes:

darryl
02-05-2010, 05:38 AM
That's kind of what I was thinking- heat the whole thing until the shaft is also hot, then swish it around in cold water to cool it quickly. Not sure if the aluminum will pass the elastic limit and actually stretch slightly, but it's worth a try. All you need is a kitchen oven and a sink full of cold water.

Then there is the hydraulic method. Find a bolt the same size and thread as the set screws. Drill a hole the length of the bolt. Probably a garden store variety bolt would be best, as you could almost poke your finger through it-

Anyway, you need a piece of drill rod that is a close fit through the hole. Pack the hole with grease and screw the bolt into the hole with teflon tape. Insert the drill rod til it's tight- then smack it a sharp one. Which way the grease will go is anybodys guess, but maybe it will form a gap between the sleeve and the shaft. You have the option of filling the set screw hole with penetrating fluid or grease as well, before you screw the bolt in.

If it seems like the grease is getting pumped in and not just squirting out somewhere, treat a few more holes the same way.

Another method would be to squish the aluminum into expanding slightly. Sounds counterintuitive, but it can work. I've done it. You need a steel support piece which has a curve on it matching the OD of the aluminum, and a second piece the same which you hammer on. Stack it up on an anvil or something. Probably need help to hold things while you smack the upper block. Work the whole length of the sleeve, and turn it 90 and work it again.

oldtiffie
02-05-2010, 05:59 AM
The underlying assumption here with regard to heating is that it will have an even effect on the part and that it will expand and contract evenly accurately and symmetrically.

It may - and then it may not.

If that outer part distorts the situation may be worsened.

A "slip fit" is very "tight" as regards limits.

If either part has distorted or been "dented" or if the parts have corroded or "galled" together it may be difficult to remedy - the more so if there are more than one of those causal events.

I note that the Op has not said that damaging or destroying either of the mating parts is an option thus far.

JCHannum
02-05-2010, 07:48 AM
I note that the Op has not said that damaging or destroying either of the mating parts is an option thus far.

Once the O/A torch comes out, that point has been reached. Generally, heat only serves to expand both parts, sometimes after cooling they can be separated, but the usual outcome is galling and damage or destruction of one or both parts.

I have had very good luck with Kroil and time in these situations. WD40 is not a particularly good penetrating oil. What materials are the two parts? Are they both steel? I do not see where aluminum is mentioned.

oldtiffie
02-05-2010, 08:06 AM
Agreed Jim.

A lot of stuff I've seen like that is "bronze" as it is easily cast and machines well, is very stable but is prone to a a build-up or patina of verdigris (green PITA stuff) which can "grow" and adversely react to some lubricants.

If the instrument is permanently housed in that unlined and apparently non-insulated weather-board (here) - "clap-board" in the US? with high humidity and low temperatures with long periods on non-use and/or minimum maintenance, I could well imagine that it would be "hard to move".

If the lubricant or verdigris "cooks" and hardens during heating, I could well imagine that it would not help matter much.

Same applies to the the "whacking" as any bruising or denting won't help much either.

I hope it all works out well.

Smokedaddy
02-05-2010, 09:54 AM
Thanks so far, here are a couple more pics ...

http://www.pbase.com/smokedaddy/image/121697882/large

http://www.pbase.com/smokedaddy/image/121697883

-SD:

Carld
02-05-2010, 10:19 AM
Again we don't know what the metal is we are suggesting things to do with.

I would use an abrasive cutoff wheel in a die grinder and split it long ways and make a new one. When you put the new one on use antisieze on it and a slightly looser fit.

The only other alternative is to press it out and that may have some issues causing damage to the part you can't easily make.

oldtiffie
02-05-2010, 05:59 PM
http://www.pbase.com/smokedaddy/image/121697882/large

http://www.pbase.com/smokedaddy/image/121697883

I can't really tell whether it is steel or aluminium - although it seems to be aluminium.

If it is aluminium, it may not be best to use a cut-off wheel.

If any of those screws have dented or raised a "dimple" or a burr and the parts have been rotated, the dent of burr may have galled - and "locked up".

In those sorts of arrangements it is perhaps best to have the shaft "relieved" by say 0.050" where the screws are positioned so that any denting etc. will be contained below the cylinder mating face.

If some-one has got a bit "ham-fisted" and over-tightened the screws it will not have helped at all.

The grease (??) looks to have hardened and oxidised as well.

I cannot see any grease or oil nipples either.

Smokedaddy
02-05-2010, 09:06 PM
For material type, looks to be steel.

-SD: