I have made a boob

Hi everyone
Can I pick your brains please, I have done my first bit of tuning on my Myford 10 lathe this morning, because I am fitting a Multifix tool post I am having to make a new post so I decided to make it in two parts , I have made the bit that is going in the compound from the bottom but I made a bit of a boob , I am going to have 2mm milled of the top of the compound and I forgot to take that into account so I have to find a way of mounting it to turn the shank down 2mm,extending the thread won’t be a problem though because as I have the thread already I can do that by hand.
Anyone have any suggestions because I don’t really want to make it again.
Dell

Without knowing what equipment you have available to use make suggestions a bit hit and miss, but my go to for this would be to hold the head in some soft jaws that have been turned to suit the part.

Martin C

Bore the end of a short piece of thick wall tube to take the base ring leaving a stop ridge. Put a slot in it so it can close up when held in the 3 jaw chuck. Insert the base ring, hold the pair in the chuck and put a centre in the end. Trim down with light cuts.

With a centre in the end it will be decently stable. The ridge in the tube stops it all disappearing up the headstock. I'd seat it as far into the chuck as you can whilst still leaving room to work as the holding power of teh jaws is compromised towards the tip due to clearance induced tilt and, usually, wear.

If you don't have apiece of tube to hand roll your own out of a short steel slug. 3 mm - 1/8" wall on the gripping bit and similar ridge depth will be fine. Just make sure you have corner clearance right at the base. Needs to be thin or the chuck won't be able to close it up.

Clive

Similar to the above, but not needing any closing up or gripping action: bore a solid piece of bar to the head diameter. Superglue it into place. Support with a tailstock centre.

You are not going to get it hot enough nor put enough torque into it to worry the superglue bond.

If its not a daft question, why are you making the stud in two parts?

I admit I dont know the construction of the top slide (I assume you are shaving off 2mm to lower the toolpost) but if there is a hole in the compound with a counterbore accessible with the slide dismantled then some sort of stepped bush to hold a HT bolt might be an option.

The head of the bolt could be thinned and the bolt be a press fit into a shallow counterbored hole in the bush.

Ian P

Couple of parallels against teh chuck face, push work against those as you grip in 3-jaw and remove parallels before turning(light cuts)

Softjaws better if you have them

Thanks for the replies

the largest part of the bit I have made doesn’t really do anything apart from sitting in the counter bore in bottom of compound so I am wondering if I put a couple of parallels in the chuck for the part to sit on while I tighten it up then remove thee parallels of course, I only need to turn one mm off for 2mm .

JasonB

I was typing when I see your post great minds and all that.

Ian P

there was no specific reason for making it in to parts other than I didn’t want to bore the holder out again mainly as I haven’t done any boring yet , so I would either have to make a one piece shaft and a sleeve or how I am doing it because the Multifix has a 10mm hole in the top and an 18mm counterbore that is 14.9mm deep .

Dell

Might I ask how deeply the 10mm male thread on the lower part enters the 10mm female thread on the upper part?

In other words, where your drawing says '10mm internal thread', and you had to add "xx mm deep", what number is xx?

You say you did not want to bore the 'holder' out again but then say you have not done any boring. In any event what part are you referring to by 'holder'?

As I understand it the Multifix splined body is bolted to the topslide and is then permanently stays in the same place and does not need to be rotated.

IanP

Ian P

Sorry for the confusion I just meant I didn’t want to bore it, if you look at picture it’s the bit top centre that I don’t want to bore

DC32k

the top bit will have just over 10mm internal thread , I don’t want to go much deeper because the bit that goes in the counterbore is only going to be 14.5mm.

Dell

I wonder if that is a little too deep. You will have to drill (8.5mm?) slightly more than the 10mm to be able to tap the threads. The drill will have a point on it which will go even deeper (roughly 2.4mm for an 8.5mm drill).

It might be worth drawing a cross section of the upper bit to determine exactly how much material is remaining and adjust if necessary.

So you think maybe 8mm would be enough internal thread , I could possibly drill most of the way then grind a flat for last bit so like an endmill?

Dell

I'm not precious about my machines but I don't think I would machine (or gets someone else to do it) 2mm off the thickness of a small lathe topslide.

It would be better to machine 2mm off the bottom of the centre post of the Multifix or possible counterbore the topslide hole 2mm deep so the Multifix post drops in.

Not knowing the Multifix product I dont know if the central post is hardened or whether its design would allow 2mm to be removed, but 1mm off the central hub and a 1mm counterbore in the slide would preserve strength/rigidity.

Based on your first drawing it looks like the topslide casting is more than 8mm thick, is that before you take off the 2mm?

With your two part post, tapping a shallow blind hole you are not going to end up with many threads engaged if its M10 coarse (its 1.5mm pitch). Since this is a Myford lathe 3/8"BSF (or 3/8" UNF) would be a better thread choice.

I still recommend making a stepped bush and inserting and standard hex bolt installed from the slide underside. In fact if the stepped bush had a tapped hole then the bolt could screw into that from the top (to hold the toolpost central block down.

Ian P

Think I would have put a M10 thread onto the bottom of the stud as well and then the lower part becomes a round "tee nut" . Couple of spanner flats on the 18mm dia or tommy bar hole to tighten it down. Easier that a short blind thread up it's bottom.

As the tool posts are metric I can't see a problem using metric sizes and Dell seems to think in metric as his sketches and text shows.

I suggested imperial only because of the finer pitch (and have not researched Dell's postings) which would give better thread engagement

Tee nut is what I was suggesting with my stepped bush with threaded hole, the one thing we dont really know is whether its essential to take 2mm off the top of the topslide, plus it seems Dell is trying to make use of the parts and work he has done so far.

In the end its up to each individual to do a job to his/her own liking, certainly there is more than one way to skin a cat but to me, the two part stud is not the best solution.

Ian P

Edited By Ian P on 26/02/2023 21:06:34

The trouble is the hole in the compound is only 11mm or whatever that is in imperial that why I can’t use the T nut idea,

pas for milling 2mm off the top of the compound, I understand it’s acceptable to mill up to 5mm off the top the compound is 14mm thick .

Dell

Not sure if this helps any, but there are some fairly detailed photos of an ML10 topslide in this ebay listing:

**LINK**

https://www.ebay.co.uk/itm/Top-slide-assembly-unused-appears-to-be-still-factory-greased-Myford-ML10-/115705948249

ended because ‘there was an error in the listing’ … so they may not be there much longer.

MichaelG.

If you are prepared to mill off 2mm then opening up the 11mm hole should be a doddle.

Actually there is no need to enlarge the hole, An M10 threaded stud will pass through into a tapped hole in a part you press into the counterbore (that exists?) on the underside of the moving part of the topslide.

Ian P

Just to confuse the issue … Here’s another ebay listing which appears to show a significantly different casting

But it also shows the counterbore:

https://www.ebay.co.uk/itm/373788047760

**LINK**

MichaelG.

The Multifix tool-post will be fairly hard. I certainly would be reluctant to attempt to machine what is a fairly expensive item.

I'd assumed that the 2mm to take off the top-slide was to allow the multifix toolholder and tool to drop down to lathe centre height. In that case reducung the height of the central post would not be an alternative.

For the hold-down bolt, I'd go for something similar to the Myford item shown above possibly with a grub-screw to prevent rotation when tightening.(apologies for layout ) I don't think that the 18mm dia. feature is that vital, but could be a separate bushing.

Edited By Clive Brown 1 on 26/02/2023 23:14:58