Stuart Twin Victoria (Princess Royal) Mill Engine

[JasonBModerator @jasonb]

Rounding over would be quite common in which case a taper pin would look better than a threaded hole to lock the pin. Forming a boss on the sides would also not be out of place.

[Martin ConnellyParticipant @martinconnelly55370]

I see from one of your pictures from 21 June that you have a 4 pin ER nut wrench. I cannot tell from your photos if the nut is one with a bearing or not. If you have milling cutters in an ER collet being pulled out there are a number of things that I would recommend, one is the 4 pin wrench which you have, another is a collet nut with an internal bearing and a third is that the inside taper of the collet chuck should be clean but with a fine smear of oil to allow the collet to close up easily. The tool shank and bore of the collets should be oil free and the collet slots clear of debris. The recommended torque for ER nuts is quite high and the best way to achieve this is with the bearing nut tightened with the 4 pin wrench and a correctly sized single ended wrench to suit the flats on the collet chuck. If you have a collet chuck without flats (there are some about) then spin up the grinder and put some on it. I, and I expect many people, have never had a milling cutter pull out of an ER chuck when using it following these recommendations.

Martin C

[JasonBModerator @jasonb]

From other threads I think it was the head pulling down not the cutter.

As you seem to get a better finish along the X axis then might be worth just turning the work around rather than do a Joe Pie and tackle all 5 in one go. What works on his bridgeport may not on a benchtop hobby mill.

[Dr_GMJNParticipant @dr_gmjn]

Thanks both.

The tool didn’t move in the collet, nor the workpiece in the vice. After it grabbed, and damaged the vice, I was able to continue with much smaller cut depths. The thing is, if you look carefully at the witness mark (which leads to the cut in the vice) it’s a significant depth and distance that the tool dragged itself along. Seems like a load of deflection must have occurred if that was the case.

Re. the forked ends: I think I’ll go with rounding them, and some small chamfers on the boss and shoulders. I can’t make the raised cheek plates without thinning the forks, and I’d rather not do that.

I understand if rounded, the locking bolt hole would be right on the tangent line and wouldn’t look great. Do the taper pins fit in parallel drilled or reamed holes? If I do this, are they drilled with the rods in place? My intention was to drill and ream the forks to 3/16” (as I did with the brass sliders). If this is the case, what’s the best way of holding the rod in place while doing these operations? Do the taper pins have nuts to draw them in (like on the connecting rod crank end adjustment)? If you just tap them in with a hammer and drift, is there a risk of damaging something on assembly (e.g. the slide bars), and how do you disassemble them?

Thanks.

[JasonBModerator @jasonb]

The one in the photo is a 1/16" taper pin – 1/16" at it's largest point tapering at 1:48 for which a taper pin reamer has to be used. Depending on the length you would drill the assembled parts 1.4mm and then ream the hole with care.

Much like a morse taper the pins are self locking are gently tapped in with a hammer and need drifting out from the other end to remove. A bit of creative clamping allows the two parts to be drilled as one.

You could actually assemble the conrod, fork and 3/16" pin off of the engine place onto the lower slide bars, add the top ones and then fir piston rod and the other end of the conrod.

[Martin ConnellyParticipant @martinconnelly55370]

The taper pins lock in the same way a Morse taper does. They do not need a lot of hammering to put them in place or to remove them but they stay in place under normal circumstances. I think the imperial taper is 1:48 and the metric equivalent is 1:50. You need a taper reamer to suit your preference and you can buy tapered pins to cut to size. There are plenty of examples of machine tools with handles held in position by taper pins.

Martin C

Jason typed faster than me

Edited By Martin Connelly on 05/07/2023 20:32:18

[Dr_GMJNParticipant @dr_gmjn]

Thanks both, I think I’ll get a pin a screamer and do it that way then. I don’t have the plans to hand, but I’m wondering if I can use the same reamer for the crank pin bearing.

[Dr_GMJNParticipant @dr_gmjn]

Posted by Dr_GMJN on 05/07/2023 21:44:06:

Thanks both, I think I’ll get a pin a screamer and do it that way then. I don’t have the plans to hand, but I’m wondering if I can use the same reamer for the crank pin bearing.

Hmmm autocorrect!

* taper pin and reamer.

[JasonBModerator @jasonb]

Do some practice ones first, at that size the reamers are very delicate and there is a lot of engagement.

Hold the pin against the job and measure the diameter where it will exit and drill right through that size say it's 1.4mm, then go half way with a 1.5 so there is a minimum of material for the reamer to remove.

[Martin ConnellyParticipant @martinconnelly55370]

This is a taper reamer, size is 1/8" so it is 1:48 taper with the 1/8" being the larger end. The cutting length is about 2" so you can work out that the other end goes down to about 3/32". The pin is a 3/16" pin and goes from 3/16" to 1/8" so they do not match, I would need a smaller pin or a larger reamer depending on what I was going to be doing. The larger pin suits the existing taper pin holes on my lathe which is why I have it, the reamer was just the first one I picked up but thought the differences in sizes was important to point out. Not all taper reamers fit all pins, they have to be sized to each other. I hope this answers your question regarding where they can be used.

Martin C

[Dr_GMJNParticipant @dr_gmjn]

Thanks both. Presumably the 1:48 taper angle is per side rather than overall?

Should each end of the pin protrude slightly above the part?

I drew out a 1/16” pin on the fork, and it looks like it would need quite a few diameters and depths drilling to minimise material removal. Should be OK though.

[JasonBModerator @jasonb]

Yes you tend to leave a bit of the head sticking out and also some of the smaller end so you can use a drift if it needs to come out again

For this application where it is simply retaining the pivot pin you could get away with just having the tapered hole in the top half of the clevis and the pin so about 2/3rds the total.

Edited By JasonB on 07/07/2023 19:40:30

[Dr_GMJNParticipant @dr_gmjn]

Drilled the counterbores on the fork bosses:

Also chamfered the bosses.

Then drilled the pin holes:

Turns out the pre-ream drill I used was too big, so the reamer didn’t cut anything. I measured the drill at 4.7 (same as I used for the brass sliders), but…anyway.

Made some filing buttons:

And filed the rounded ends:

Then chamfered the sides:

Progress so far:

I suppose I could hand ream the holes and brass blocks at 5mm, (which is about 0.009” more than 3/16&rdquo. I’ve already got a reamer and some 5mm stainless rod. Seems par for the course for me these days to end up correcting something, so no big deal.

[JasonBModerator @jasonb]

You were lucky with the brass, 4.7mm is a bit large for reaming 3/16" on that sort of size I tend to go 0.2mm smaller so 4.5mm or 4.6mm

[JasonBModerator @jasonb]

You were lucky with the brass, 4.7mm is a bit large for reaming 3/16" on that sort of size I tend to go 0.2mm smaller so 4.5mm or 4.6mm

[Dr_GMJNParticipant @dr_gmjn]

Posted by JasonB on 09/07/2023 06:53:58:

You were lucky with the brass, 4.7mm is a bit large for reaming 3/16" on that sort of size I tend to go 0.2mm smaller so 4.5mm or 4.6mm

Double- checking, I put 4.6 on the brass block drawing, 4.7 on the forks. I must have looked it up twice and rounded up on one, down on the other, or something daft. Anyway, I assume if I run through them all with a 5mm reamer I can do it by hand? Presumably it will self-centre, or should I setup in the mill?

Re. The face bosses – seems like there’s about 0.3mm excess on the faces compared with the cross-piece, so to make them equal I could machine them leaving the bosses raised. Question is, having filed the rounded ends, I guess I might end up with a step on the radiussed end. Less chance of the if I mill them on the R/T, but easier to setup in the 4-jaw and turn them. Also I’ve not got a milling cutter with a 0.3 tip radius, but I’ve got plenty of turning inserts with 0.2mm radii, which would make a nice fillet.

Any thoughts?

[Bruce VoelkerdingParticipant @brucevoelkerding91659]

Dr_GMJn

Taper Pins are made to 1/4" per foot taper on the DIAMETER – not the Radius as you queried on 7/7/23. 1/4" per 12" is 1:48 on Diameter, 1:96 on Radius. Note METRIC Taper Pins are 1:50 taper.

When I use Filing Buttons in the Case shown above, I would make the Pivot Pin about .016" longer than the Sum of the thicknesses of the Part plus the 2 Rollers. I would put .008 x 45 deg Chamfers on both Ends – no Threads.

Instead of the Nuts, clamp the assembled Parts in the Bench Vice (I have replaced all the serrated Jaw Inserts in my Bench Vices with smooth Brass Replacements). Note at this Stage the Part and the Rollers are free to rotate independently. I install a Screw in the Part to control its Position and I file until both Rollers rotate freely. It is satisfying to feel both the Rollers rotating – you know you are at Size and have not damaged the Roller Diameters.

The Rollers are used unhardened and will last "forever".

[JasonBModerator @jasonb]

If you use a 5mm hand reamer that has a long tapered lead so should be OK to do it by hand and probably easier than trying to set up again under the mill spindle. Or you could put the parts into a vice that is free to move on the mill table which should allow it to self ctr.

Doing the forks on the lathe would be easiest, stop just short of the rounded end and it won't show if you take too much. I'd probably just turn the end of a bar to 5mm, cut a short thread and fix part with a nut.

[Dr_GMJNParticipant @dr_gmjn]

Thanks Jason, that worked ok, although they might need a bit more hand rounding to get them spot-on. The bosses aren’t too pronounced, but they have equalised the thicknesses of the three bits of fork. I won’t bother increasing the side chamfers, because I think they look ok as they are:

Still got to ream them, and I need to get some taper pins and taper reamer ordered. I think now they look much more refined and match the rest of the engine a bit better.

Edited By Dr_GMJN on 09/07/2023 19:02:34

[Dr_GMJNParticipant @dr_gmjn]

Posted by Bruce Voelkerding on 09/07/2023 14:01:34:

Dr_GMJn

Taper Pins are made to 1/4" per foot taper on the DIAMETER – not the Radius as you queried on 7/7/23. 1/4" per 12" is 1:48 on Diameter, 1:96 on Radius. Note METRIC Taper Pins are 1:50 taper.

When I use Filing Buttons in the Case shown above, I would make the Pivot Pin about .016" longer than the Sum of the thicknesses of the Part plus the 2 Rollers. I would put .008 x 45 deg Chamfers on both Ends – no Threads.

Instead of the Nuts, clamp the assembled Parts in the Bench Vice (I have replaced all the serrated Jaw Inserts in my Bench Vices with smooth Brass Replacements). Note at this Stage the Part and the Rollers are free to rotate independently. I install a Screw in the Part to control its Position and I file until both Rollers rotate freely. It is satisfying to feel both the Rollers rotating – you know you are at Size and have not damaged the Roller Diameters.

The Rollers are used unhardened and will last "forever".

OK thanks, I’ll re-calculate and amend my drawing. I’d assumed the 1:48 taper was along one side only (in plan/elevation view).

I did leave my in-hardened buttons loose, but the jammed occasionally during flatting, hence the damage. I think the forks look ok overall though.

[Dr_GMJNParticipant @dr_gmjn]

I might have a go at the connecting rods next. I guess I have no choice but to make a tool for turning the end radii.

I seem to remember some talk about fish bellied rods being more accurate than the plan versions, but can’t find it in the thread. There was some mention about the machining method bring wrong (which I did find), but no mention of the profile.

Maybe the plan is ok after all?

[JasonBModerator @jasonb]

Which radii are you talking about

I'll dig a post of mine out later for the bellies

[Ramon WilsonParticipant @ramonwilson3]

Hi Doc, I'm sure Jason will provide you with a good method to follow but for what it's worth I described making fish bellied rods on HMEM when making them for the Waller engine.

 

As you can see they are composite which makes for much easier machining – you can find the details here post #16 onwards (The description of making them is further on at the start of the second page of the thread)

Here's an image of the pair I made for my twin Vic using the same method. These ran at many shows over many years without showing any signs of their composite make up. The big end 'blade' was an integral part of the shaft.

 

Good to see you making progress – none at this end I'm afraid

 

Best – R

Edited By Ramon Wilson on 11/07/2023 07:45:23

Edited By Ramon Wilson on 11/07/2023 07:57:28

[Dr_GMJNParticipant @dr_gmjn]

Posted by JasonB on 11/07/2023 06:48:55:

Which radii are you talking about

I'll dig a post of mine out later for the bellies

The end radii of the circular section rods, where then run out into the rectangular ends.

[Dr_GMJNParticipant @dr_gmjn]

Posted by Ramon Wilson on 11/07/2023 07:42:03:

Hi Doc, I'm sure Jason will provide you with a good method to follow but for what it's worth I described making fish bellied rods on HMEM when making them for the Waller engine.

As you can see they are composite which makes for much easier machining – you can find the details here post #16 onwards (The description of making them is further on at the start of the second page of the thread)

Here's an image of the pair I made for my twin Vic using the same method. These ran at many shows over many years without showing any signs of their composite make up. The big end 'blade' was an integral part of the shaft.

Good to see you making progress – none at this end I'm afraid

Best – R

Edited By Ramon Wilson on 11/07/2023 07:45:23

Edited By Ramon Wilson on 11/07/2023 07:57:28

Thanks Ramon. Glad to see you posting here again.

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