Reconditioning a Relmac lathe

[Robin Hewitt]

Only a suggestion, a ghastly, unauthentic bodge that may cause you to vomit, but here goes :rofl:

Turn and bore the bearings to size.

File the externals so they can fit perfectly in line

Jig up square and all assembled

Inject Loctite (or metal loaded epoxy if slack), in to wherever you poured the molten metal before

Robin

[BillTodd]

What you need is a portable boring machine that'll go down to your spindle size (Unfortunately my ancient Buma bar is 2" minimum)

The smaller ones used to be common place in motorcycle and scooter dealers (in the days when you could get your machine re-bored for two shillings and tuppence). Any long established dealers in your area? They may have one you could scrounge?

They're still being made, so there's still a use for them somewhere:

http://www.allstates.com/ShanghaiBoringBar.html

[irving2008]

Only a suggestion, a ghastly, unauthentic bodge that may cause you to vomit, but here goes :rofl:

Turn and bore the bearings to size.

File the externals so they can fit perfectly in line

Jig up square and all assembled

Inject Loctite (or metal loaded epoxy if slack), in to wherever you poured the molten metal before

Robin

What you need is a portable boring machine that'll go down to your spindle size (Unfortunately my ancient Buma bar is 2" minimum)
...

Robin, I had considered the idea of boring oversize, then fitting bronze bushes which have been lined with white metal and bored to size. But the effort of this outweighs the idea of boring to size since these bearings if done right, will last another 100 years or so.

Bill - interesting but don't see how to get it parallel to ways... these boring machine assume a cylinder block or similar to sit on that is a known perpendicular to the hole to be bored.

My current plan is to make a saddle out of 1/2" ground plate, approx 8" long which will be bolted to the apron in place of the real saddle and will carrry two braced uprights with oilite bearings in which will run the spare spindle from my breaker lathe and this will be driven by a small, 1/4HP AC motor via two pulleys and a v-belt that I have lying around. This needs a cutter rotating at 400 - 500rpm so gear down 3:1 (1450 -> ~500RPM). I will use my existing MT3 boring bar and draw bar The back end of the saddle will have a gib plate cut at 60deg to match the existing dovetail. I'll fit a handle to the leadscrew at the headstock end in place of the gearwheel to allow the boring assembly to be wound into the headstock...

[BillTodd]

interesting but don't see how to get it parallel to ways... these boring machine assume a cylinder block or similar to sit on that is a known perpendicular to the hole to be bored.

You just need to create a known perpendicular with a couple of right-angle plates, referencing the face and edges of the lathe bed - The boring bar has a built-in three point reference to centre itself in the bore.

My current plan is to make a saddle out of 1/2" ground plate, approx 8" long which will be bolted to the apron in place of the real saddle and will carrry two braced uprights with oilite bearings

Ok Sound's like a plan, but seems like a lot of effort - you are, after all, making a complete new spindle boring tool. If you have any kind of removable lathe spindle head (e.g. Southbend type) that could carry a long boring bar, it could save you a lot of work.

Are you going to use the existing lathe to line bore the two new bearing holes in the saddle part? (see attached example) (this would ensure the height and alignment of the boring spindle is correct for the lathe).

Just a thought; What about a couple of self-centring bearing blocks and a length of shaft - i.e. cross drill the shaft at one end to hold a cutting tool. Mount the shaft and bearing between centres while you tighten the bearing blocks to ensure everything is in-line.


BTW How big are these Relmacs?

The pictures show the set-up I used to line bore the bearings for a motorcycle headstock.

The 1" steel bar is held in a collet at one end and a revolving centre at the other. It is cross drilled to hold a cutting tool (broken 6mm carbide end mill).

The second picture shows the use of a DTI to set the cut depth.

You could probably use a similar set-up to bore the bearing holes for you spindle boring tool - that way the new holes would be perfectly aligned with the old spindle.

[rotorhead]

What you need is a portable boring machine that'll go down to your spindle size (Unfortunately my ancient Buma bar is 2" minimum)

The smaller ones used to be common place in motorcycle and scooter dealers (in the days when you could get your machine re-bored for two shillings and tuppence). Any long established dealers in your area? They may have one you could scrounge?

They're still being made, so there's still a use for them somewhere:

http://www.allstates.com/ShanghaiBoringBar.html

Hello Bill,

I'm new on here, but would appreciate a picture of your Buma bar

Regards,
Chris(rotorhead)

[onecut]

bill,intresting to hear you have a buma portable borer l worked for them for about 20yrs off and on good little machine although l would say that as l milled all the parts they were first made with power stations in mind we done alot of breakdown parts for them obviously when a power station is having a problem with a part they dont want to stop production of electricity so to avoid stripping down lengthy and expensive procedure they bored part out where it was sleeved it finished bored it only replacing part when it was unsalvagable that mean they could plan a big strip down and have alternate backup whilst replacing it a lot of them went overseas it was only a small outfit but had a good reputation-happy days look after it will be rare in a few yrs time