Member postings for Steve Withnell

Hmmm Not an expert at this, and I've always used the typical forms, not really thought how they might change on a small lathe or had any particular problems. One thing about small lathes is that they are used to cut much smaller components and that means that the cutting edges do need to be kept super sharp.

There has been some debate about carbide inserts, which can have a (in comparison with a sharp HSS edge) large radius, because they are manufactured for larger production machines.

I'm really interested in what the more experienced have to say on the topic.

Steve

I've ended up with Windows 10 on my laptop - it kills the "sleep" and "hibernate" on Dell and HP laptops, including mine. Managed to get "sleep" fixed, but not "hibernate".

Win 8.1 was the last chargeable upgrade, going forward Windows will just follow a rolling upgrade programme that's free at the point of upgrade. However, expect more ads, expect a lot of pay as go go services (Microsoft Office badged as 365 has been sold on a rental basis for maybe five years now). As you've found out Clive, MS seem to be very determined to follow the Google model of grabbing every morsel of personal data they can.

Read Google's Privacy statement to see just how intrusive they are. Even talks about capturing telephone numbers dialled, when and for how long. They already use 'private' eMail content to drive context sensitive advertising.

As for Win 7, suspect it's out of support soon, so they will be no where else to go except Linux?

The old UNIX bumper sticker "Live free or die"

Steve

I've been buying increasing amounts of kit, mainly components and bits of test gear off eBay from a variety of Chinese / Hong Kong sellers. Their feedback is often less than 100%, yet I've had 100% service on every purchase. One purchase took 3 months to arrive - £125 of test kit. I eMailed the seller after 4 weeks and he responded immediately with an offer to mail out the kit again or refund my money. I said I'd wait, when it turned up it had been in a Swiss customs warehouse for at least two months. The rest of the kit typically pitches up in about 3 weeks.

I bought some quite expensive test from Germany (it was all up cheaper than buying from the UK) and the service was excellent. So it's not that Foreign sellers are scammers, but that scammers are scammers.

Steve

The other example of this is flywheels with curved spokes - whatever perceived advantage there is must be lost if it's turned the other way?

By the way Maurice lovely job! I've a little woodworking job on the bench at the minute, but with  malicious(ish) intent in mind . If it ever gets finished I'll post it.   Just need work to get out of the way for  while.

Steve

Edited By Steve Withnell on 08/08/2015 08:36:18

only if the lathe is being carried on the back of the Great A'tuin!

Parting off blade is too thin for the diameter of the work and set too low? I've seen that somewhere else

Steve

Edited By Steve Withnell on 01/08/2015 09:35:48

Before you ream to size, I'd try a test on some similar material, the last one I did, I wasn't 100% happy with the fit, it felt a little loose so tend to bore to a fit now, but that's with 3/8th axles, might be less of an issue with 6mm.

MIght have been the reamer or my reaming technique though! One thing to check for is that you drill to the correct size before reaming - the reamer mustn't have too much work to do or too little.

I can't see any issue with using 6mm instead of 1/4inch. The thing I like about building these small engines is that you can vary things to suit and try out your ideas in the build. There tends to be only a few critical dimensions to watch for.

Steve

Nick,

If you pass my way at all (Lancashire Riviera), you can have a couple of pints. I use about a teaspoon a week and I've rather a lot (Excelcut 401) under the bench...

Steve

Thanks for stimulating the debate! No stupid questions, only stupid answers...

Paraffin is usually £6 a gallon at the hardware shop and I thought that was expensive - remember petrol is 85% tax.

Steve

That's a good idea Ian, thanks.

I've made both components seperately now, but I could drill tapping size through the sheave and pulley in a couple of places, drill the sheave clearance and countersink. Then tap the pulley 7BA and screw together with a couple of c/csnk screws. The mod would almost be invisible. Also once the timing is set properly, I can still take the strap off and tighten the grubscrew i nthe sheave if I need a bit of extra bite to stop the timing slipping.

Sounds like a plan!

Steve

Learning to be skilful maybe

For the base, I don't like the idea of keeping the base flat and then just making the recesses for the nuts (as per plan), it seems wrong to me. I was thinking about milling (no more filing!) a slot right across the base of the crosshead guide, half the width of the base and half the height (4.5mm) of the square section of the base. I think the guides will sit better on the cylinder cap and it may well look more attractive too.

What do you think?  Maybe round the corners though.

Steve

Edited By Steve Withnell on 19/07/2015 11:45:22

Still filing... I keep rotating and flipping over the guides to try and keep everything square. I've also gone a bit over size - the centre part is just slack at 9mm, should be 11/64ths. Trick is not to make that worse whilst I get the ends to size. I am pretty close to done, I've been using the shank of a 9mm drill to gauge the size of the gap, so I think now I'll make the crossheads and use them as a gauge to finish out the fiing work.

I've also now worked out precisely how I should have tackled this job!   Never mind,  filing is quite therapeutic...

Steve

Edited By Steve Withnell on 19/07/2015 10:11:01

So now we are here in the build:

And I need to add the cross head guides (just perched on top to show the idea):

What you get from Stuart in the kit are these castings. I've already had a whinge about how rough these are compared to the castings Stuart used to ship.

First step is to give them a good fettling and get into a decent state. Then I clamped the pair together so I could drill a hole through the top and bolt them together. Difficult to see but now a lot of the rough edges have been filed flat (not optically flat, but homeworkshop amateur with a file flat)

I then used a filing button to centre the hole - there is no where to measure from, so the hole just needs to be centred the best I could.

Having made a short length of 5BA stud I then bolted them together so they are always aligned for the next operations.

The next plan was to mill out the guide slots with an 8mm slot drill, but mine are not long enough, needs a long series type to go all the way through both guides, so resorted to filing them. This is really good filling practice!

As the old boss used to say, "making good progress but more to do"... Problem with the crosshead guides is that they are a centrepiece for the engine, so not only have to work mechanically, but look good too...

Steve

Thanks Graham, I saw that, I was just trying to avoid registering for yet another forum...

Steve

Next step is to drill the "table" to mount the cylinder. If you remember, the James Coombes is a "Table Engine". It doesn't mean the engine sits on a table, like most models do, but rather that the Cylinder sits on an entablature - a table. The next challenge is to fix the cylinder square and dandy in the middle of the table, as it is the central, vertical axis through the engine.

Not shown on the plan, but documented in Andrew Smiths guide to building the engine, he describes drilling a central 1/4" hole through the middle of the table, then making a little fitting which is a disc sized to the engine bore, with a turned spigot that is a push fit into the 1/4" hole. I didn't really like the idea at first and took a halfway house approach.

I made a shallow 1/4" recess in the table and made a temporary jig to centre the cylinder

Then I mounted the drilling jig over the jig so that's centred. The holes can be roughly centred against the marking on the table, but a final check is to setup to drill the rear most hole, then wind the table to the front most hole and the drill should pass right over that hole. If it doesn't, the jig needs rotating a bit. (Bear in mind the rear of my table plate is a datum and the rear edge of the vice is set to the axis of the mill).

Then finally, the finished operation:

The next thing I did was to drill through the table into the cylinder, the orientation is set by using a straight edge against the cylinder port face and the marking out on the table, and then clamping in down. The little jig is used again to to keep the cylinder central.

Here is the work all clamped together and set up on the mill, for drilling through 7BA tapping size -

Once the cylinder is tapped it can then be mounted on the table.  Two points to note here,  Stuart supply 3/8" studs,  which are too short,  so I made some 7/16" to ensure a proper hold in the cylinder (thanks to Clive on the stud length).   The clamps got in the way so I could not drill all six holes at one go,  and it had to go back on the machine to get at the final two.

That's all for now folks!

Steve

Edited By Steve Withnell on 18/07/2015 09:54:18

Fact is anything you have posted is stored on the site and can be retrieved "My Posts"- so "tittle tattle" gets killed stone dead as soon as you retrieve the post. If what you posted was fair and reasonable, tell the supplier to suck it up. If what you posted was damaging to their reputation, then watch out.

Also bear in mind that suppliers are also present on the site even if they only read posts rather than contribute.

Better you stay and contribute than leave - if you leave the other guy won.

Steve

Before I crack on with any more James Coombes build pictures, here is a very useful jig I made for the Stuart Victoria.

The James Coombes and Victoria share the same cylinder, so the jig works for the JC too. First off I turned the spigot to the diameter I intended to bore the cylinder to. In this case that very popular metric value - 25.4mm.

Since inner diameters are more difficult to measure than inner diameters, this is a simple gauge to test the cylinder bore.

Then I mounted the sigot in the rotary table and drilled 7BA tapping size holes to the PCD indicated on the Stuart plan. Key point here is that if you bugger this up, it's just a short length of steel bar, not a very nice, expensive casting. Once the holes are drilled correctly, you then have a drilling jig, which reduces the chance of an upset with the cylinder by quite a bit.

Then finally, the end caps needed drilling, so to ensure they were drilled correctly, I bored a shallow recess to take the inner spigot of the end cap and could again drill the end cap in exact alignment with the cylinder.

Final trick is that because the jig is quite thick, having drilled the holes out clearance size, it can be used to keep the tap straight when tapping the cylinder.

Bear in mind that even if you only have one cylinder, the jig will be used twice for the cylinder and twice for the end caps and once for the boring, so it has a lot of utility for such a simple thing. The next project on my list is a twin and I will definitely be making a jig to support machining the cylinders.

Steve

Yes please!

Steve