Indexing arms on dividing head are spinning freely

Hello, I am new to the group today so will be heading to the "introduce yourself" page shortly. I find myself here because I am about to use an old dividing head for the first time but immediately ran into a problem.

The brass indexing arms fit over the centre shaft but there is nothing to provide any tension/friction to keep them in place. The shaft has what could be a circlip grove in it approximately 1mm out from touching the arms, so I am assuming there is a brass? washer type piece that presses against the arms to stop them spinning freely.

Could someone tell me what pieces are missing please. I.E brass shim or spring or something I haven't thought of?

Many thanks,

Jim.

There should be something to provide some friction so perhaps a wave washer and circlip are missing.

I'm guessing you have the same head as me:

https://eur.vevor.com/dividing-head-c_10129/dividing-plate-dividing-head-4-100mm-for-rotary-tables-in-model-hv-3-4-5-6-p_010947578525

Firstly, Welcome.

How old, and how big is the Dividing head?

It sounds as if you have the Dividing Plates and Handle that go with the Dividing Head.

What make?

Pictures always help.

Spares might be available.

There should be a thin, spring steel "washer" (For want of a better word ) that fits into the groove and presses onto the two arms, to provide eniugh grip to stop them moving by accident.

Do you have the chart giving the turns and holes needed for each of the plates to give a required number of divisions? If you have; check it; errors have been known! I was caught by incorrect info on the set up for 13 divisions; and then found other errors.

The chart will be specigfic to your particular DH. Depending on the make, the ratio of the worm and wheel could be almost anything. (36; 40 or 90:1 seem to be popular ratios. ).

On a Vertex HV6 Rotary Table, you would be looking for part No. 52 which would be described as a "Sector Spring"

Howard

Jim

I suspect you are missing the part shown in the photos below. It is a dished half washer and fits in the groove you mention to apply some tension on the arms to keep them from moving but still able to rotate to position them. Should be easy enough to make something suitable.

John

Many thanks for all replies so far.

Unfortunately there is no makers name I can see but I assume reasonably old. As for how big, what is used as a reference for DH size?

Due to its age and not having been used for at least 25 years, and to clean it all up so I can use it, I decided to strip it. Unfortunately I found the "brake" is broken. Without a makers name, how would I go about getting spares?

I have brazed it just now but not sure how strong it will be. Sorry for the almost certain incorrect terminology.

Re the indexing/selector arms, I will try and find a wavy washer first but make a brass one if not.

Yes I do have the handle/pin and 3 plates.

I have photos I would like to post but can't find how to do that despite trying hard.

Thanks again.

Jim.

Welcome to the nuthouse

Some places want you to drink a yard of ale in one go to become a member

In here the right-of-passage challenge is to figure out how our pictures system works

I made my replacement from a spare brake hose clip I found in a drawer:

https://www.amazon.com/Empi-98-6685-B-Stainless-Steel-Bug-Bus-Ghia-Squareback/dp/B076DLRNWL

Lets see if the advice Frances gave works for me.

I have just noticed some replies to this post show on my phone, but not on my laptop.

being pessimistic, have doubts about bthe stregth of the repair.

BUT, if you use your lathe to make a new one, the brazed D H lock might last long enough for you to complete the machining, and so be able to fit a replacement locking device.

It might even be worth extending the machining on both sides a little further towards the holes.

FWIW, I would suggest making the bore as close a fit on the mating part as possible, to minimise the bending of the arms. It might be worth extending the depth of the slot until it intersects the solid part of the clamp, to make the arms more flexible and to move the point of bending.

The worm is likely to be single start, so if you count the teeth on the wormwheel, that should tell you the ratio, which will be a start.

Somewhere on here, there was a spreadsheet showing the calculations for a Rotary Table with a 90:1 ratio.

Serach for HV6, spreadsheet. That should allow you to find and copy the spreadsheet, so that ikt can be edited to suit your purposes.

If you copy it and amend the formulae from 90:1 to the ratio of your DH,you should be able to construct, and print a chart showing the divisions available from your DH and the division plates that you have.

Good Luck!

Howard