Old rollocks

I have been asked if I can machine the shaft of this rowing boat rollock. Its a brass casting I think. The shaft diameter is approx 15mm and it needs to be 13mm.

I suggested drilling out the hole it goes into but for whatever reason thats not an option. My first thought was to clamp to an angle plate that is mounted on a face plate. I have a Myford lathe.

Maybe some one here has a clever idea.

hold the shaft in the chuck to hold it somewhere near put angle plate up to fork end and pack and clamp. put angle plate onto faceplate or if you have a mill reverse bore outside of shaft. balance faceplate with counter balance weights if turning.

David

Cast some "Cerobend" (low melting point alloy) around one side of the "U" end. Hold shaft in the chuck and clean up the cerobend end. Turn it around in a 4 jaw chuck so that the shaft is ready for machining. Put a small centre into the tailstock end of the shaft.
Material will be bronze, not brass and will turn nicely, but like you, the shaft needs all its strength, so don't reduce the diameter too much.
BobH

Hi Andy

Pardon my morning pedantry.... I believe that 'rollock' is a colloquialism of 'row lock' ... no doubt some one will respond with the rhyming 'b******S'

George.

Cerrobend or Woods metal is very good for this type of job, it melts in hot water but is quite hard at room temperature and, of course, it can be used over and over again.

I first encountered it when I started working for a company repairing jet engine turbine blades that are very difficult to hold for machining due to their shape.

The blades were placed into a mould with locations to match those on a milling fixture, filled with Cerrobend and then machined after which they were dunked in boiling water to remove the Cerrobend.

If the item is to be welded or silver soldered then it is vital that every trace of Cerrobend is removed to avoid contamination. It can be pickled but I not now sure what with.

Brian

It looks as if the curve of the Row-lock is over the center line of the spindle, if so put spindle in chuck and drill center and then reverse, set up between centers and turn spindle down to size., Simples.

Clive

+1 for BobH. This is the stuff. Can you still buy it or has the H&S confined it to everlasting damnation along with Easiflo 2 ?

Almost certainly. But in most cases they are referring to working with the stuff 8hrs a day, 5 days a week. Once a year will be less dangerous than a woodbine once a month.

Regards,

Richard.

That's an interesting option. It does seem to be available in small quantities on ebay from Germany

- It's also known as Wood's metal or Rose's metal FYI.

Jon

It can still be obtained, try a Google search. I also found a meterial from Bendalloy Co called Polybend and their site states,

'For those customers that are not sure what Polybend is or what it is used for, we will supply a sample pack of 500 grams, this will produce ½ a litre of fluid when melted, for £20.00 sterling, this includes shipping. UK only, for other countries, please enquire.'

They also supply Cerrobend and other materials.

Usual disclaimer.

Brian

AlecTIRANTI as advertised in ME sell woods metal £40/Kg

Some good ideas have been suggested so far to accurately reduce the diameter of the shaft. Whilst I'm sure some or all of them will do the job I wonder (especially if this is just a one-off) if its not just easier to use a file.

Sometimes its worth looking at a task from a different angle, if you wanted to escape from a desert island the lack of a lathe would hardly be a problem.

The finished part does not have to be a precision fit in its socket, fifteen minutes work with a decent file and a vice are all that's needed. With steel rule and a micrometer getting it suitably round and straight enough does not need that much skill. (OK I do know you might not have a file or vice on the island so you might have to rub it on a rock)

Not that it makes much difference but the metal is probably bronze not brass.

Ian P

I would explore the option of drilling the first, say 25mm, on the boat and then do as Clive suggests.

Reason is that removing 25% of the shaft, at the main point of stress, would be avoided. But maybe it is well over-engineered so thinning would not be a problem?

How about cutting the round bit off at the collar. Drill and tap the 'U' shaped section and insert with Loctite a new 13mm dia brass or stainless steel pin. Possibly use the sawn off pin if it will be long enough after having turned it down on the lathe.

John

Edited By Journeyman on 30/06/2017 15:03:49

Its's a crutch- iron made of brass.. for the pedants… I had a similar job on some for a waterman's cutter they were made from cast bronze/ admiralty bronze. The shaft was worn on the back side so the answer was to lop of the shafts and drill and tap M12 in the shank and then machine up some stainless shafts the right diameter cut a thread and then screw and braze.

The makers of Cerrobend and Cerromatrix used to make several variants with different melting points. Pedantic, perhaps, but the can't all be the SAME as Wood's metal. I'll admit 'similar'.

I think I have their data sheet somewhere.

Best regards,

Swarf, Mostly!

Rowlock.

Not to be confused with a bollard, futtock or a brass monkey...

Thanks for ALL the replies. Some very clever ideas there, I knew there would be from this forum!

From filing to Cerrobend not sure which way I will try yet but I will post photos when I have done it.

Off topic - I was at Goodwood Festival of Speed yesterday. Some amazing engineering achievements to see. Unfortunately I forgot the PIN # for my Swiss bank account.

Well three months later I have finally finished this job for my friend. I decided to buy a boring head and then a left hand turning tool. It doesn't take much for me to convince myself that I need another tool !

OK this finish is not great but it will serve the purpose. Most difficult part was of course holding the crutch as nothing was 'square' on it.

Again thanks for all the suggestions!