Member postings for jonathan heppel

Look up Rich King. There's quite a lively scraping scene in the US. I get the feeling that about the only scraping left in the UK is done by the very few reconditioners remaining, eg ZMT the Hardinge guys and the Bridgeport and S&B specialists whose names I forget- oh and D,S&G, but I think they would all regard yours as a scraping job. A surface ground piece would normally need hand finishing anyway. In the States they prefer to scrape all surfaces, but a specialised slideway grinder can leave a rough enough finish and it's quite common just to scrape the mating slide.

Scraping is by no means entirely obsolete, but largely only seen on the finest machinery these days. I am not refering to the butchered "flaking" on oriental machinery which the machinery dealers use as a selling point to the unwary.

If you've never tried scraping, it can be quite hypnotic, but by heaven is tedious!

That's interesting, Julian. I've never heard of vesconite but it's obviously well established. Disappointing that they are so secretive about it, particularly after 50 or so years. It seems their main market is comparatively big stuff machined from stock rather than finished inserts. I'm gratified to see it on a loco though- good example of appropriate technology.

Thanks for the replies. Casting your own is a good solution for specials and threads but less so if it can be done with standard components and more demanding situations.

Cabeng, I'm very pleased to see your post. It has puzzled me for ages that even new designs specify eg bronze for jobs that are not really suited to it even disregarding the cost. I was beginning to think that there must be a technical reason not to use them. If bronze is necessary for aesthetic reasons, then it would even make sense to line it with a polymer shell, so in the unlikely event of wearing it out, it could be easily replaced on a still unworn shaft.

I think polymer bearings are well worth looking at. I've started a new thread on it, because my searches suggest that they are not much known about among modellers, though there was a series some 30 years ago in ME about a DU bearinged spindle.

Does anyone have any experience with polymer bearings such as DU or DX from GGB (Glacier) or the more modern composites from Igus? I come across them frequently at work and they are for many purposes greatly superior to white metal (Babbitt) and bronze. They excel with soft shafts, low surface speeds, high loads and marginal or no lubrication.

I expect some scoffers, but the fact is there's been a huge amount of research into plain bearings since Isaac Babbitt. They are not just cheaper, they are usually better by a margin. They aren't split which is a limitation in some cases but I believe are well worth looking at for eg axle boxes, links and one piece mains.

There is the related topic of polymer seals, which can make the oil-free steam cylinder a real possibility (even superheated) as in the Spilling engine and in industrial oil-less piston compressors.

Any comments?

Edited By jonathan heppel on 19/02/2014 12:23:25

It's worth mentioning that it's by no means obligatory or necessary to set the compound slide over at all, particularly if there is no side rake on the tool as with most modern tips. True, you get better chip clearance with the set over method, but for common modelling pitches and depths of cut, it makes little difference.

The Hardinge HLV-H manual actually recommends cross slide feed even though the compound is set over for retracting purposes. (I know GHT said otherwise but in this he was mistaken.)

Ps compound set over is more universal in the US, but historically less second nature this side of the pond. 

Edited By jonathan heppel on 07/02/2014 20:33:10

You could settle the PA story by measuring the rack- that's what I would do.

It's worth mentioning that it does depend on the job. Overpacking does little harm at low circumferential speeds but can be catastrophic at high speeds due to the grease churning and overheating. Truly high speed spindles have circulated oil or oil mist systems, sometimes using the pumping effect of the taper bearings themselves. In reality, the speeds and sizes commonly seen don't need such measures.

Why do you need to know? It looks like like any old imperial motor. 5/8" shaft if I remember right. You can still get them, assuming it's a standard size, which it looks like. If it's just poorly,take it to a rewinder.

If the coils are dead, cheapest option is probably to change to metric, though it's more work.

Thanks for the link, lots of help and interest from that site. Funnily enough, ME did an article on it in the 3rd June 1994 issue, front page and all!

Considering the quantities of beam, marine and stationary engines out there I'm surprised that there seem to be so few of this type, particularly since they look perfectly doable without castings or cnc.

I have a multifix and I love it. Having 40 positions instead of 2 or 4 gives a huge boost to flexibility and you'll find you don't need so many holders. Chamfers are easy- just index the tool round. If you cut screws with an angled top slide you don't need to reset the post. Setting tool height is a doddle- index it round to the tailstock centre. There is also the obsolete and rare hss holder that has rake built into it for toolbits (if you can find one). The cylindrical bar holder is ideal for an auxiliary spindle for pcd's etc. They are also super rigid.

While they are a bit of a luxury, there aren't any similar luxuries that you'll have in such constant use.

I can't comment on the copies but I think Rotagrip are trustworthy.

Hello all. I have an irrational dislike of crossheads and would like to build a John Penn trunk engine, such as the Crimean war survivor from the SS Xantho in Oz. Has anyone built one of these and are there any drawings available? It is such an iconic engine that there should be lots of info but I haven't found much online.

I've seen Rich Carlstedt's superb USS Monitor engine but it's not the same.

I'll try the WA museum also but I thought I'd ask here first.

I once had an Edwardian book that was filled with lots of useful chemical recipes for home and small workshop use. One of the more interesting ones was a set of instructions to brew nitroglycerine, though it did tell you to be careful.

Between the wars, my dad bought gunpowder over the counter, buried a bomb in Dartmouth College's parade ground and blew it up as part of graduation celebrations. He and his chums were just told to reinstate it.

I can't help feeling that we've become a nation of wusses to be scared of something that is really quite easy to test in a safe manner using the brains that the good lord gave us.

Disposing it with the powers that be is a bit rude since it costs a great deal of money to do it officially which is a service we all pay for.

I would say, however, that if you keep it, do label it, even just "Unknown Acid", since you never know that the proverbial bus with your name on it isn't on its way.

Recently there was a good thread on derusting with hydrochloric acid. Most acids will do this.

If you work much with steel, you can save lots of dosh buying black bar instead of bright and pickling it to remove scale, with the bonus of being more stress relieved.

Some 40 years ago there was a series in ME titled " Blower charged two stroke engines", if memory serves. The author firstly experimented with a vertical twin, then built a rather pretty V4.

I hope I'm not retreading old ground but if you are interested in micrometers check out the COFES micrometer website- a very fine collection which is well documented.

I checked out GaryM's suggested site and there's an ex college DS&G for £4000. The stuff of dreams! If only I could persuade my wife.........

The Empire Luers style blade that Eccentric use are IMO better than the tapered Eclipse style. They are only sharpened on the front face, since the top face is hollow ground which compresses the chip a little. MSC offer them with a carbide cutting edge. The holders are easier to make, since the sides are parallel. They work well with no back rake even though it's recommended. Make a toolpost at the right height and it won't need adjusting and you can easily vary overhang.

Ps you only need a couple of degrees clearance.

Edited By jonathan heppel on 30/11/2013 11:19:45

I've wondered about that myself. I've seen cross slide mounting morse attachments on larger machines to power drill (not bore btw) for production, so can only assume the the toolholder is for the same job. The only other use I can think of is for holding small boring bars in arbors or collets. Can anyone else enlighten us?

What about a travelling steady or one of those toolpost mounting steady/cutting combo tools? Shouldn't be a problem.