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Smart and Brown Sabel

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Philip Powell11/02/2011 09:08:25
68 forum posts
15 photos
Richard
 
Wow , thanks for your reply, very detailed. I'm reluctant to mess around with the present gear as I can still use the machine although anything needing backgear is out. I going to hang on and see if I can find a spare first, who knows one may turn up. If I can't find another gear then I will have a try at repairing this one or sell the lathe.
 
Thanks again.
 
Phil.
ady11/02/2011 10:12:13
612 forum posts
50 photos
I redid my backgear with t6 aluminium, but almost half my teeth were missing, the old girl had taken a hammering and needed a total fix.(the piccy is in my profile)
I turned the teeth off the mandrel after measuring everything up then made a t6 copy with an undersized bore then made a quick shallow 8tpi screwcut through the bore for the undersize bore aluminium to "squish" into when I fitted it.
Fitting was a case of battering it on to the mandrel, protected by a hard plastic drift.
The alternatives in my mind were a keyway or a grubscrew which would involve more drilling and messing about on the mandrel and involve uneven stresses on the cog when it was working hard and doing intermittent heavy cuts.
 
The instant difference in the usefulness of the machine is like night and day, especially with tough jobs. The backgear can also be disengaged at the end of a screwcut job and the saddle whirled quickly back by hand to the start of a screwcut while still directly attached to the mandrel via the changewheels, very useful for jobs like metric cuts when you don't want to disengage the leadscrew nut, then re-engage the backgear cluster(kinda like a lever operated idler cog system) and hog another cut in the thread.
 
With only one tooth missing you're in a really annoying position but the fix, whatever you do, is well worth the effort.
 
It took me 14 months in my spare time to build the bits like the milling spindle to actually do the job I wanted to do, so be patient, you shall definitely be rewarded if you do it right.
 
One area you CAN still use your backgear for, because only one tooth is missing is removing stuck chucks.
 
Put a block of wood in/under the chuck, braced against the bed/ways and run it backwards by hand, with the backgear engaged(avoiding the broken tooth bit of course).
You'll soon get the technique for your own lathe once you get a stuck chuck, lol.
 
I did mine in aluminium because it deforms to any tooth errors(I'm only an ama-teur and a hacker) and hopefully the aluminium is weaker than the rest of the drivetrain, so I now have a sacrificial part which can be redone by me if another disaster strikes, I cut 2 cogs at the same time and parted off in the middle, so there's now a spare small cog lying somewhere in the pile of junk and swarf littering my workshop.

Edited By ady on 11/02/2011 10:39:14

Terryd11/02/2011 13:18:41
avatar
1946 forum posts
179 photos
Hi Richard,
 
I've not heard of 'spherical' cast iron, did you mean spheroidal cast iron or is 'spherical c.i.' something I've not come across before?
 
As far as I know (I'm no expert in metallurgy) spheroidal C.I. contains spherical nodules of graphite which gives it ductility rather than the brittleness of normal C.I.
 
Regards
 
Terry
Philip Powell11/02/2011 16:07:23
68 forum posts
15 photos
Hi Ady
 
Quite a story there. I would never have thaought of making a gear from aluminium as I thought it would be too soft, you have proved otherwise.
 
"One area you CAN still use your backgear for, because only one tooth is missing is removing stuck chucks."
 
I suspect thats how the gear was damaged in the first place.
 
Thanks for sharing your repair.
 
Phil.
Richard Parsons14/02/2011 16:52:59
avatar
645 forum posts
33 photos
Terry I have always known it as 'spherical cast iron'. Probably becaust no one in our part of the world could spell 'spheroidal' -except old Doc Gleesinker and he would probably have proscribed some black Jollup which tasted 'reesty' and some other hookum (which stunk like the bottom of a polecat ferrets cage) to slap on it!
Terryd14/02/2011 21:54:52
avatar
1946 forum posts
179 photos
Hi Richard,
 
I just tried searching for 'spherical C.I.' on Google which mainly came up with cast iron spheres, a load of old bollards I think .
 
Best regards
 
Terry
Tom Broekmeulen28/08/2012 12:44:50
1 forum posts

Can someone send me some picture of the gears. I obtained a model Sabel with some gears missing but i dont know exactly which ones. perhaps some of you have a manual or drawings?

Please contact me

Jeff Dayman28/08/2012 17:08:29
2356 forum posts
47 photos

Hi Philip,

Not sure how much of a copy of the South Bend lathe your Sabel is. I can tell you that one broken tooth in the back gears will do no harm at all on the South Bends. I have a much battered 1949 SB 9" lathe with flat belt drive and before I owned it several teeth were broken off the back gear with no real harm done (as long as they are not adjacent teeth). The only sign I see of the broken teeth is that back gear is not quiet. I regularly tap up to 1/2"-13, and drill large holes up to 3/4" in steel in back gear with no trouble. I wouldn't fret about the teeth unless the gearing is actually causing a problem for you.

You might check the South Bend forum on www. practicalmachinist dot com for info on spare parts. If the S&B machine was a true copy of the SB, an SB backgear might fit, and there are guys on the SB forum in USA who can supply them.

JD

Philip Powell28/08/2012 20:15:37
68 forum posts
15 photos

Jeff. My goodness I had forgoten all about this thread. I have managed to fix my Sable by buying a complete Sablel on ebay and taking off the bits I needed and sold most of the remains. I got back almost what I paid for the doner Sabeland got myself a replacment backgear as well a a few useful spare parts. My Sabel is running very nice now.

Tom. If you join the Smart & Brown Yahoo group you can download the manuals and see many photos of other Sabels. That reminds me I must post some pictures of my Sabel.

Thank guys.

Phil.

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