Member postings for Simon Williams 3

Good Evening all, just a minor update to complete my experiments with superglue and epoxy.

Step 1 - make another test piece, as the original has now been soldered together, so to make the next experiment as near the same conditions as possible, not to have the surfaces locally contaminated by lead solder, I made another pair of test parts from the same material. As near as I can judge it the sizes and clearances at the interface between the two parts were the same as the original.

Step 2 - degrease with acetone, then glue together with run of the mill B&Q own brand (Diall) superglue. Leave to cure for 24 hours, ambient temp' about 20 C. Withstood 25 ft-lbs, failed at 30 ft lbs

Step 3 - clean carefully and glue with Araldite - the slow setting high strength version. Leave to set for 24 hours, ambient temp about 25 - 30 C (heatwave!) Apply torque as before, joint withstood 75 ft-lbs, failed at 80 ft-lbs.

Step 4 - remove remnant epoxy, degrease and glue with freshly bought Loctite 401. I chose not to use activator, as the instruction sheet for 401 indicates that activator is only necessary on difficult materials and may be counter-productive on "normal" materials such as steel. Instructions also say that full strength is reached in 72 hours, so I left the test piece to cure for 5 days. Ambient temp' was 16 - 20 C. Joint withstood 65 ft-lbs, failed at 70 ft-lbs.

So - soft solder wins way out in front, Loctite 638 about half the strength, but superglue carefully applied and left to cure for plenty of time pips it. My worry here is knowing what result I have achieved - have I got a 25 ft-lb superglue or a 65 ft-lb joint.

Thanks as always

Simon

Wow, thank you all for your interest and helpful comments.

In no particular order -

Surfaces cleaned immediately prior to Loctite application with acetone on kitchen roll. Actually not impressed with the oil removal results of this - applying Baker's fluid to the join showed beading on the surfaces, leading me to believe that the join needs something a lot more aggressive to be effective at de-oiling the surfaces. But then Loctite is supposed to be tolerant to a bit of good honest workshop muck, so part of my experiment was to see if this was a limiting factor.

Working gap (as near as I can measure it - 1 or 2 thou, probably nearer 1. Certainly there is a positive gap as the two parts slide together without any interference.

No Loctite primer or activator.

Ambient temperature about 16 - 18 C over this last weekend

I too expected 638 to be nearer the strength of soldering - this was a bit of a surprise, though 50 ft lbs /70 Nm is a pretty respectable result and ample for the purpose.

Obviously pinning the two parts axially would effectively lock the two together for all time.

Materials - the 41 mm a/f hex "nut" is EN32B, the smaller pinion and stub are probably EN1A, sold as "GCQMS". From the way it machines there ain't no lead in it.

I like the suggestion of trying the same with superglue and epoxy - will investigate and report back.

Many thanks

Simon

Being an inquisitive soul, I have been making some experiments with the relative strengths of Loctite.

First to set the scene. Some of you will be familiar with this as being the mandrel gear for a pre-historic Myford S7 with the Mk 1 QCGB,

xxxx

The one on the left is the proprietary Myford 30/12T original, the one on the right is my version of the same thing with 17 teeth on the smaller gear. I made a 17T gear on a stub shaft, and soft soldered a 30 T gear onto the stub.

I was curious to know if I could have used Loctite, and how strong is the soft solder anyway.

So here is a dummy gear cluster, with hexagons cut instead of the two gears:

xxx

For the sake of completeness here is a picture of the two component parts:

xxx

There are, as you will have noticed, remnants of Loctite on the interface between the two parts. To scale the area of the interface, that stub is 0.625 OD +/- about 3 tenths, and the bore is 0.375 ins long by 0.625 OD - minus nothing plus maybe 5 tenths. So a "place fit" rather than a push fit. I didn't make any attempt to polish the mating surfaces - the bore is straight off a reamer and the stub is straight off the lathe tool, which is exactly how I made the parts of the original gear cluster.

So I tried assembling the two parts with differing grades of Loctite. Then I broke them apart in torsion holding the large nut (41 mm a/f) in the vice and applying a measured torque to the 19 mm a/f "pinion" with a torque wrench. To be strictly fair the torque is applied only one sided - so it is a cantilever load on the join - but that is how the assembly will be used in real life. I applied successive and increasing torques to the assembly increasing in 5 ft-lbs increments until the joint failed. The two torque wrenches I used are in good condition but not formally calibrated and are the micrometer type.

This is what I measured:

Loctite 638 12 hours cure, failed at 60 ft-lbs, withstood 55 ft lbs.

Loctite 638 repeated, 17 hrs cure, same result

Loctite 243 (Nutlock) 2 hrs cure failed at 15 ft-lbs, withstood 10 ft-lbs

Loctite 542 (Thread Sealant), 3 hrs cure, failed at 30 ft-lbs, withstood 25 ft-lbs.

I then tried soft-soldering the two parts together, using 60/40 resin cored solder with additional active flux, this failed at 110 ft-lbs withstood 105 ft-lbs.

If anyone can suggest other grades of Loctite which might be of interest to get into the magic three figures I'd be interested to try them out.

Rgds Simon

I managed to get one apart recently, having tried the wedges and failed, by drilling a hole down the centre of the arbour, into the void at the back of the chuck. I filled the hole with oil, then pushed a short piece of rod as a piston into the drilled hole. I was surprised how hard I found myself hitting the end of the piston to get the hydraulic shock enough to pop the taper.

And of course I was lucky it was a homemade arbour and had been left soft so I could drill down the centre of it.

Regards Simon

Things will get very exciting very quickly indeed if you manage to remove the right angled valve directly on top of the cylinder, shown in Geoff Walker's post above. It would be prudent to review your life insurance before trying.

The regulator the OP has pictured - and the similar one also shown - all have a 5/8 BSP LEFT HAND thread which screws into the female outlet of the right angled valve on top of the propane bottle. The valve is intended to be a simple on/off valve so the gas bottle can be isolated safely for transport etc.

Always close the bottle valve after using the system, or leaving it unattended. It's the ONLY valve in the system which will function as an isolating valve preventing leakage or gas escape. Neither the regulator nor the control valve on the torch are specified for this essential function.

Inspect the hose regularly - it will be fine to begin with but will de-grade relatively quickly. Budget on replacing it every five years whether it leaks or no.

BOC insist that regulators for oxy-acetylene only have a five year (from date of manufacture) service life and are disposable - at several hundred quid a kick. I don't know what the manufacturers recommendations for these regulators is but I would imagine it's much the same.

In the same vein as "never leave the chuck key in the chuck" never try to remove that right angled valve from the top of the cylinder. You won't succeed (they're TIGHT) and if you do...

May the Good Lord have mercy on your soul.

Stay safe

Simon

....and check the speed, as I have a hazy recollection that the one I used to have had a 6 pole motor on it. So if you wanted to swap the motor it would dance like a thing possessed running with a four pole motor.

Though it's possible I've got muddled between this and a Wicksteed saw I also had back in the mists of time. The motor plate will tell you what the nominal full load speed is.

HTH Simon

Experiment away, it doesn't really matter. So long as you have enough gas to be able to light it and get a nice stable flame you're on a winner. It's not going to go bang.

Screw the adjuster on the regulator in half way or thereabouts, light the flame keeping your fingers out of the way. Now vary the torch control and see the difference between not much and Crikey!

Twiddling the regulator at the bottle only really affects the magnitude of the "Crikey (that's hot)" setting - otherwise the control at the torch handle throttles the amount of gas reaching the nozzle, So the regulator acts mostly as a maximum control.

The thing that really affects how much heat you get is the size of the burner nozzle. Which burner have you started with? There will be a four digit number (e.g. 2942) marked on the side of it. This describes the size of the burner orifice jet and hence the amount of gas it can pass.

HTH Simon

Good afternoon, I'm after some advice about how to select the appropriate type of oil seal (lip seal) for my application.

I can find plenty on what's available, but nothing on why to choose one type over another.

My application is to replace the shaft seal on a hydraulic gear motor, nothing special, it's an 18 mm shaft in a 30 mm seat, seal length 7 mm. Load's of 'em on the net. Working pressure probably 100 - 200 psi, as the oil its contains is at return (tank port) pressure. Shaft rotation is reversible and typically 2000 rpm.

What are the rights and wrongs of a single lip seal against a double lip seal, and why. The original wasn't spring energised, I guess the oil pressure against the seal energises it, but what little I can find on the 'net says that seals for use with oil would normally have a spring. I have no idea if the one I took out (double lip, no spring) is the appropriate choice, but it has lasted years so it must have had something in its favour.

Thanks, as always, in anticipation of some help.

Best rgds Simon

I've recently realised that my difficulties with a parting tool are mostly related to using one three jaw chuck. Closer inspection reveals that the jaws are ever so slightly bell mouthed, so I suspect the work is walking in the jaws.

The chuck in question is a Pratt Burnerd 160 mm self centreing three jaw. I bought new jaws for it - not convinced this has cured the problem reliably. I'm using an inserted tool courtesy of Jenny at JB tools, or a standard Eclipse parting tool 3 mm wide with no top rake. The lathe is a Mk 2 Bantam. I even modified the top slide slightly so I can lock the gib nice and solid. As far as I can tell the head stock bearings are adjusted right, though they could be a shade loose as I'm frightened of over cooking it. I don't think the Dickson toolpost is the best tool mounting for a parting tool, but its other advantages go without saying.

I bought a (brand new) 5 inch TOS chuck ages ago, but have hardly used it until buying a backplate recently to adapt it to fit on my Bantam. I just know if I say that this has been the cure for my parting off problems I will regret it, but so far so good.

Very - no extremely - not convinced about using power cross feed, but Andrew is right, you need to keep the tool loaded or it chatters like fun, and yes it's a mistake to slow the revs down more than say one gear (25% or so) to reduce the chatter and the heat on the tool, as the chip load goes up significantly. I part off with one hand on the cross slide dial and the other holding an oily paintbrush in the groove.

Hand number three is hovering over the stop lever.

Best regards

Simon

Does anyone know if the deposit and the heat affected zone from using cast iron welding rods - presumably nickel based - are machinable? I'd hate to hit a hard patch at the interface between the weld and the parent material and knock the edge off one of my gear cutters.

Rgds Simon

Edited for the obligatory typo

Edited By Simon Williams 3 on 02/06/2020 11:03:19

Edited By Simon Williams 3 on 02/06/2020 11:03:51

If you had a crown on your belt sander pulley the belt wouldn't run flat. Hence it needs (the added complication of) a tracking adjustment.

Rgds Simon

And if you are interested to see it in practice, here's the Keith Rucker video I referenced

**LINK**

As you can see, apart from the fact that the finished article is multicoloured, it makes a very workable repair.

Best rgds Simon

There's something not right here.

I haven't understood how the second (front) belt is tensioned - there seems to be some sort of screw under the edge of the intermediate pulley.

On my RF25 (Alpine Engineering badged) the intermediate pulley stack is an idler mounted on an arm swinging around the centre column. For all combinations of belt and pulley positions the movement of the motor is sufficient to tension the pulleys. It gets a bit close the the limits of the guard in some combinations, but it does work provided the belts are the intended length.

Swinging the motor tensions both belts. Is that the case with this machine?

I wonder if the second belt (on the spindle) is a bit too long - using up more than its fair share of free travel?

Ostensibly it looks as though the machine has been fitted with the wrong pulleys from birth - but that statement has other ramifications.

Would you like to measure the OD of each sheave on the three cones, and also if possible identify the length of the belts as fitted. Oh, and the nominal speed of the motor.

Then a photo of the label showing the nominal spindle speed for each belt position please.

I think I've got a programmable calculator program to calculate the PCD length of the belt path for a given shaft spacing and sheave size somewhere, if not there's sure to be one on the 'net. We can then model the dimensions of the drive and see what's going on.

An intriguing riddle, but it's only geometry.

Best rgds Simon

Summat might odd with this.

Before I make a fool of myself making all sorts of irrelevant suggestions, could you put up a photo or two of the belt drive aspect of this to show the parts involved?

Look forward to helping out.

Simon

Good Morning all,

There are two different though related processes being discussed here, and hence the debate over the heat input.

Brazing is where you heat the whole item - or enough of it locally - to get the bronze filler to flow into the work. This implies you have a general temperature suitable to get the filler to melt and flow. Very difficult to control where the filler goes, other than a thin layer on the surface of the hot area, or pulled by capilliary action into a fit-up gap. A Sievert or a Bullfinch gas torch would be suitable for this process, provided the burner was chosen appropriately.

Bronze WELDING, where the heat input is very localised (though possibly with the use of a pre-heat to control distortion etc.) This uses the heat of the flame to melt the filler metal locally, so it fuses but by manipulation of the heat you can build up a fillet or an insert of bronze material locally. This is the process you can see Adam (Aborn 79) or Keith Rucker use for the task being discussed.

The necessity for a significant localised heat input makes bronze welding the territory of oxy-acetylene, though you can do it with oxy-propane if needs must. But you need the small intense heat source to locally melt the filler deposit as you add more to build up the weld metal in layers. The skill is in manipulating the heat input so as to melt enough but not too much.

TIG brazing is the same process - the terminology is very confused. However the visibility difficulties with having to use a welding mask to see anything at all means that using a TIG torch as the heat source is a whole lot more difficult.

Having built up the filler sufficiently then you machine it back appropriately to give the gear tooth profile. You might well end up with a gear tooth of bronze amongst a whole lot of iron ones.

Keith Rucker does exactly this job in one of his planer restoration videos, he makes the point that you need to grind the parent metal out to get back to good material to which the bronze weld will adhere.

The tooth resulting looks a bit odd; provided the process is done without overheating the silicon bronze filler rod and burning off the alloy constituents the filler is potentially stronger than the parent cast iron.

HTH Simon

Edited for typo

Edited By Simon Williams 3 on 01/06/2020 10:38:01

That's mighty fishy!

If, as I understand it, it is a plain key I would sensibly expect that the grub screw would bear on the top of the key, which says to me that the pulley bore has slipped and is somewhat chewed. Trying to tighten the grubscrew to compensate means that the screw is trying to take the drive torque, as the key isn't helping. That in turn chews the motor shaft.

'Fraid you're going to have to dismantle enough at least to get the pulley off the motor and see what the problem is.

As others have said beware of the second grubscrew in the same hole below the first, also another screw (or screws) at 90 deg to the obvious one.

Good luck, and do keep is posted

HTH Simon

I'd like to add to Robert's suggestions and recommend that the new user of anything machinery related should visually check the earth connection for robustness and security before going on to do a circuit check. Robert rightly makes the point that a whisker of wire contacting the frame of the machine will permit enough current to flow to satisfy a multimeter; one way around this is to be sure that a robust physical connection is present.

That probably means taking covers off etc; that in turn begs the question of invalidating the warranty. I'd hope that a responsible commercial vendor would be able to get himself past that hurdle and not get all hoity toity about it. The user needs to know of his own certainty that the earth is satisfactory.

HTH Simon

Edit - for clarity

Edited By Simon Williams 3 on 28/05/2020 12:11:40

'Fraid thar ain't the whole answer.

Bigger motors - say 4KW and up - are generally wound 400v (delta) and therefore 690volt (star).

This lets them be used with a star delta starter. This applies the line voltage (400 volts three phase) to the windings connected in star to accelerate the motor from standstill to about 80% speed.  The starter contactors then switch the windings into delta configuration and re-apply the supply, to achieve full speed and power.

The advantage is that the maximum inrush current Is reduced to about three times the full load current, and the machine gets a gentler start.

Even bigger motors  apply the same principles at higher voltages (3.3 KV for example).

So it all depends on the application.

Edit - rephrased for clarity - hopefully

Edited By Simon Williams 3 on 25/05/2020 08:54:34

OOPS!

Think I've got my lefty-loosies in a tangle. My apologies.

Bill's put it straight - thank you.

<2/10, could do better>

Simon

Mk 2 gearbox at this date, and the 2 : 1 reduction shown at the LHS of the gearbox confirms it, so the leadscrew does go right through the gearbox from one side to the other.

My recollection is that there is a woodruffe key in the bore of that gear, but the gear is only a light push fit on the end of the leadscrew so bashing it shouldn't be necessary.

Go looking for a second grubscrew - it's the sort of trick they'd play.

Two screw drivers behind the gear maybe?

HTH Simon