Member postings for Martin Johnson 1

I had a similar problem with a bar stamped "Holfos" a while back. I think I just avoided the problem in the end.

Martin

Meehanite is a corporation that licenses participating foundries to produce a variety of cast products. What is usually referred to as Meehanite is continuous cast bar - excellent quality, no hard spots but CAST IRON. What confuses the issue is Meehanite also specialise in SNG and high nickel irons with a whole range of applications from crankshafts to ultra wear resisting. Unless you specify a particular grade Meehanite means absolutely nothing.

Martin

Build something that isn't by Evans, LBSC, Young, Plastow, Greenly, Haining, ............etc

I could have been a chatbot - what a waste!

Martin

Well I was trained in a leading UK manufacturer of large marine diesels. The scene in which an external lap was put on a crank throw to "tidy it up a bit" was enacted on a daily basis here in the mid seventies.

Martin

The tubes are open. The heat sets up a siphon effect as steam is made, lost up the short leg and replenished with water down the long leg.

Just love LBSC's grasp of heat loss and radiation theory, though.

Martin

I just realized there is an easier way.

Turn a bush to fit end a so part fits to the face of the bush.. Remove from chuck.

Grip the old part in chuck by end b. Mount the bush on end a, turn exterior of bush parallel.

You now have a wonky bush with correct throw, and a datum face to plant a part finished blank completed up to end a.

Grip bush and part finished part in chuck to finish end b.

No mill required.

Martin

Hat off to you Sir.

Well done.

Martin

Make a bush, but drill or bore it in the milling machine to the required angle. You could either set the mill head over to the angle or rig some sort of sine table arrangement.

Then machine one end of the part, hold in the wonky bush (grubscrew perhaps) with the bush held in 4 jaw chuck to machine the second end.

You still have the problem of getting the intersection of the two wonky axes in the right axial position. A bit more examination of the part needed to determine where and how important it is and how the OEM did it.

Martin

Clrarances in the Clayton valve gear are really small. If there is a clash, the reverser arm is rhe first thing to give. Suggest a really careful check on clearances with the reverser arm held in a range of positions. If you dont have it held at present then it will move even wifh adequate clearances.

Martin

The Dewhurst tumbler reveRse did finally give up on my 55 year old Kerry lathe. However whatever switch you have will sooner or later give up on an inductive motor load. So after 50 years would you prefer to replace the Dewhurst or A N Other switch?

More importantly everyone is obsessed with NVR's - what about protecting the motor with a thermal trip of some sort as a fuse is not going to solve that particular problem.

Martin

The instructions for my Kerry lathe require that the holding down bolts should be barely finger tight and the suppot at each end of the bed is fibre board.

I don't hold with the Myford practice of using an inadequate bed stiffened up by sundry bolts, stands, concrete or floor joists with the added variable of an operator who insists on walking about on the elastic concoction.

Use the tailstock and you will probably need to fine tune that for a job of that length and tolerance. Mark the 12 oclock position on the tailstock centre for repeatability as well and always use the same projection on the tailstock.

Martin

The clever bit must be setting those multiple tools to correct position.........

Martin

I have been a professional mechanical engineer all my working life and a model engineer for longer. I haven't stopped learning more about material selection in all that time, so l would say a single book could not do it justice.

I dont think the repeated revision of steel grade codes in recent years has done anyone any favours (possibly excepting the EU beauraucrat mountain).

So for a beginner best advice is follow the drawing or ask club members.

If you actually know what a bar is definitely stamp it on the end, he said as a council of perfection he seldom achieves.

Martin

To which the answer is "It all depends"

In my day job in fluid dynamics, we would build scale models to flow test. Now you can scale flow to give the same Reynolds number as full size, or if it had open surface you could scale to give Froude number as full size. You cannot generally satisfy both without invevting working fluids with impossible properties. Add in that you might also want to scale for Prandtl number, Grashof, Graetz, Mach.....etc.

So it all depends on what you are trying to do. As LBSC summed it up "You cant scale nature"

Martin

I also have one of those O ring boxes, and it only rarely has the required item. Add in extra complication of material specs such as viton for higher temperatures then its a no brainer. Auction site all the way.

Martin

I ran a modified digi caliper on my lathe cross slide for a while, but found it really achieved nothing. I work mostly in metric on an imperial lathe and conversion is easy as 2 x table (0.1 mm requires 2 thou on the dial). Eventually it had some problem (cant remember now) and I couldnt be bothered to repair it.

What I do have is a long Arc Euro magnetic bar on the long axis. A very worthwhile mod.

I value the advanced features on my 3 axis Sinpo system on rhe mill, but really don't see that I could justify the expense on the lathe.

Martin

I use them as separators for horizontal mill cutters, slitting saws etc.

I think there was a Tesla turbine project on Utube used a stack of them for a rotor.

Martin

"If you have ever seen the results of fitters using a large drill's morse taper as a hammer on the blunt end of a drift to release another drill from a machine's socket you would know they are far from hard."

That would explain the marks on one of my inherited drills.

Martin

A small Stuart has recently passed through my hands, which had the displacement lubricator on the valve chest cover. It looked like it had seen a fair bit of use in that condition so I would say go ahead.

Martin

I certainly agree that Turbine Guy has done fantastic work on small turbines, including the tricky bearing issue. I do check out his thread regularly. While my needs are somewhat larger, scaling up from his work is not too much of a problem, and the scale issue should then be working in my favour.

I have started to give a bit more thought to a generator now that the rest of my steam lorry is largely finished.

My next problem is the electrical side......

Martin