Member postings for Norman Lorton

Very subtle Windy to be pointed to a half-hour German language home video 'LIVE | 2023 NitrOlympX FULL Nightshow - V8 Flames Burnouts Firework Drag Racing Hockenheimring'

But at 16m40s, I think, is your friend's steam rocket, and it certainly does shift down the drag way!

I'm sorry that I cannot offer much more help. The only clue is that other people also seem to get the 34T gear to fit and slot space runs out around 35T. Are the two intermediate gear pairs 57/19 T? Perhaps you can post a photo of your lathe end as I have done and we see if a Myford guru can spot the difference? Norm.

Hi Adam

Just to be clear, this thread about swapping the tumbler gear refers to use with the Myford gearbox. You will not need to change the quadrant that supports the gears driving the gearbox. From the attached picture you can see the locknut at the bottom that secures it. With a 24T standard tumbler gear fitted and there is about 3/8" movement left in the slot. It seems that most people can fit the 34T tumbler and there is just enough slack in that slot to adjust for that largest gear. If there is not, then you can simply hand file a little more length to the slot.

I have had quite a few enquiries for my spreadsheet so this tumbler gear swap, to quickly obtain Metric and BA threads from the Imperial gearbox, is still popular.

Best wishes

Norm

Hi Peter

I have used a Myford 7B for a while and recently added a Harrison 140. The Harrison does all the larger metal and castings and the Myford all the tiny bits in brass. Extravagant perhaps but hey what is a hobby?

Good suggestions above on the Boxfords and M250/M300. I considered lathes like the Craftsman and geared head Warcos but like you inclined to old British. I am very happy with the 140, it is a lovely machine with the VFD motor added. Nice M300s are nearer to £3,000 and I have read comment on the Harrison Yahoo website of some M300 users wishing they had their 140 back. Having said that, I would be very happy with a M300.

The 140 is the 1970s final incarnation of the L5 and then 11" series. They have metric dials and nearly all have metric gearboxes; one alternative gear set will give you all the imperial pitches. As well as 11" (140mm) swing they have a gap bed for 18" swing. If you find a nice one ensure it has all the (slightly expensive) extras. The problem for us home machinists is moving them as they weigh 750Kg, but if you have a 2 ton engine crane and can put them on a pallet, the pallets can be moved quite a way by freight companies for £80.

Have fun planning and looking. PM me if you want to ask more about the 140.

Norm.

Michael, I thought about the rotary table and a centre (cone) sticking up from the Morse taper, and decided to try it on my newly built kit. A few minutes later I realised all this talk about conical surfaces might be off-target.

Let's think about how the basic Gelbart idea works. A laser beam at, say, 10 deg strikes the vertical surface of a rod and draws a horizontal circle around that rod if the beam rotation centre is exactly coincident with the centre of axis of the rod. Displace one of the axes and the drawn circle will be distorted (to some sort of ovoid, but not egg shaped, neither is it an ellipse) and no longer horizontal. As you reduce the angle of beam incidence any misalignment of the two axes will amplify the distortion and further tilt the circle. When the incident angle is zero degrees then the sensitivity becomes infinite.

It follows that if you increase the incident angle, for example by making the rod into a cone, then the sensitivity of the rotating laser, in indicating the centre position, is reduced. My thoughts are that this negative effect of a cone applies to the conical buttons theory (sorry John and Michael). I recon that the buttons will however work well if they are conventionally parallel and stick up about 1/4", but are quite wide, perhaps 1/2" diameter or more.

I played with my rotating laser last night and found it more sensitive at 9 deg than at 11 deg, such that finding a datum point better than +- 0.001" in both axes seemed easier. You also need a target of around 1" diameter to properly judge the laser line being horizontal, at this sort of precision

If I'm wrong on the cones I will eat plenty of pie, but I think they exited stage left with a few Dodos.

Regards, Norm.

I am adding this edit to clarify that all the above assumes you are working in the cone area above the laser point of intersection.  If you want to work in the conical area below that point, then conical metal targets become useable, but only if the the total target cone angle is greater than the total laser conical angle; ideally around 20 deg more so that the incident angle is around 10 deg.

Edit number two: Hmmm, perhaps I should eat some pie as I now see from his diagrams that John was talking about using the laser cone below its point of incidence; sorry John for trying to kill off the cones. The problem with working in this laser cone area is that the distance from machine head to table starts to get a bit bigger.

Edited By Norman Lorton on 30/01/2014 14:43:05

Edited By Norman Lorton on 30/01/2014 14:51:33

Thank you to John for pointing us to the Dan Gelbart series. I have watched all 18 and they are excellent. It's a delight listening to someone who understands the science behind why stuff happens.

His part 15 of 18 demonstrates the rotating laser centre finder and I was intrigued, as others in this thread have been. Never mind the theory that has been discussed, I decided to make one and try it out. It uses the commercial laser centre finders that have been discussed (here and ME?) before and fits into a 1/2" collet. I made the angle adjustable but it worked at the first try which is around 10deg from the vertical (20deg cone).

The image worked at around 600 RPM and the polarising cap had to be removed to see it well. I obtained lovely tilting circles on machined steel for upright bar and holes. Dan Gelbart is exactly right (and who wouldn't believe his every word) when he claims 50 micron alignment precision. In my language that is two thou 0.002" and that is my estimate of what's achievable.

I have been using the static, vertical laser to find centres and edges and with the eight thou spot size would have to try hard to get +- 0.004. Now, this device is a magic dream. I have put three photos below to show the device. I have also made a quick video and posted it on this link in case anyone has not seen the Gelbart original film.

Video Link

Who else has just made one?

Norm.

Edited By Norman Lorton on 29/01/2014 15:16:40

Edited By Norman Lorton on 29/01/2014 15:37:54

Sound like you are having fun making dust! Yes, the leaded bronze seems to keep its yellow - and it machines better.

I have found that it is SAE660 and Colphos 90 in diameters 1" and more that have the silver or grey metallic sheen, often spiralled.

PB102 in sticks under 3/4" seems uniformly orange/brown on the outside. I do have some PB102 in larger sizes up to 3" and then the surface shows extrusion marks that indicate a weak spiral, but it is more orangey than silver.

Regarding sizes and identity I have seen the reverse of what somebody said to you: there is one metal retailer who supplies PB102 if it is 7/16" and under and SAE660 if it is over that size.

Norm

Oh this is a can of worms! The short answer to Adrian is that it is hard to tell. If you cut a fresh face, from my experience, the brass will leave a yellow face and stays yellow for a week. Phosphor bronze will cut yellow but turn orangey in a week. Brass will typically 'powder' as it cuts while bronzes can produce larger chips. Old sticks of phosphor bronze are more orange on the outside than old sticks of brass.

However, the only true phosphor bronzes are PB1, PB102 and (perhaps) Colphos 90, and each of these contain phosphorous. Gunmetal, SAE660, and Colphos 90 also contain lead and zinc (which is why Colphos 90 in my view should not be regarded as a phosphor bronze). The leaded bronzes do cut easier than the pure phosphor versions. Commercial SAE660 and Colphos 90 sticks seem to have spiral silver and dark patterns on the outside skin.

I have spent time looking at this realising that the correct material for locomotive boiler bushes is PB102 (copper, tin and phosphorous only). Some people seem to use the leaded bearing bronzes for this purpose and there is a thought that this material may not be suitable.

Unfortunately, I am not sure that all metal suppliers are always clear about what they are supplying.

Norm.

Thank you for the photos Jason. Although I was there on Saturday they are still good to look at, and you have photographed things that I cannot remember seeing!

The Australian chap with the V12 engined Tiger Tank was a star. He kept putting on demonstrations and taking it apart to show people; even running it when there were big engine knocks and an apparently loose flywheel. Did he fix it for Sunday?

The lighting and viewing were sometimes an issue. In my view, the best engine there was Alan Crossfield's 5" Patriot that is now painted and finished. Beautiful to see, but regrettably in a dark corner, even though near the windows.

Oh it was sad watching this poor posting slide down the 'latest posts' table with no one to answer or even commiserate Dear Moderators, is there a booby prize for anyone who receives no replies?

I should have guessed as even the great Tony @lathes said nobody knew; and people on the (slightly USA configured) Yahoo Harrison group site had raised the subject but not arrived at a full answer.

But I don't want someone else to search this site in years to come and think there is no known answer - I have now worked it all out. I fitted some gears, measured the travel with digital callipers, and found I could get 8-60 TPI from the Harrison Metric gearbox. If there is ever one other person in the world who wants to know then send me a message and I'll be happy to pass on the information.

I have a 1971 Harrison 140 with a metric Norton gearbox and thus metric leadscrew. The L5/L5A/140 manual suggests what set of drive gears to substitute to obtain 8 to 60 TPI, but gives no clue as to what the gearbox settings might be, other than giving the clue "… as for standard Norton Gearbox".

The complication is that the "standard" gearbox (Imperial?) had two thumb levers, rather than the three of the metric box, and might have used a 4TPI or a 6mm pitch leadscrew, i think.

I will measure the output with a dial gauge on the saddle, but before I try to buy the conversion gears has someone been here before and can they tell me what works?

Sorry that this is interminably boring for anyone without a Harrison!

In the Classified Adverts on this site there is a Chester Craftsman for sale - I emailed the chap two weeks ago and it was still available. It's got the 6" centre height and a gap bed; only downside is a difficult motor belt to move for low/high speeds but people have overcome that. The Craftsman is now discontinued and is the same as the old Warco BH600G that has a strong following.

I was interested in that lathe, or a geared head Warco, but I found a Harrison 140 at a small dealer. Ex. school so covered in crud and painted by a fifth former, but little apparent wear. Superb engineering that is a delight to play with. It's taken me two days to clean and partly dismantle, and another two days to make parts to fit a new dual voltage motor. But that's what we get into this hobby for!

Dehumidifiers work superbly, providing the workshop is reasonably airtight and not draughty. I have used one for six years in a large workshop (triple garage), with a well insulated ceiling but bare brick walls and solid concrete floor, keeping the RH below 60%. At that humidity there is no rusting whatsoever. As a bonus, you walk into the workshop early morning when it is 5 degC and the fact that it is dry makes it feel much more pleasant. After a few hours with electric heating it is up to 14 deg C and the dehumidifier no longer comes on because the warmed air is drier (relatively). When I leave at the end of the day the dehumidifier works hard on the cooling air to control a potentially increasing RH.

Yes, the condensing surface dehumidifier is much less effective at 5degC but at that temperature the air contains a lower mass of water, and the external air leaking in is typically colder, and thus carries less weight of water, even if its outdoors relative humidity is 100%.

Silica Gel bags simply would not cope except inside sealed plastic bags - there is far too much water to be removed.

My dehumidifier is an EBAC CD35, measures 14"x14"x28", costs around £300 and rated at 350 watts typically runs at a 30-50% duty cycle for me. Working fully I find it removes 80-100 cc of water per hour at 60%RH and 10-14 degC. They need a drain drilled through an external wall, unless you enjoy spending time pouring away a litre or so per day!

Norm

Hello Thomas

I am most happy to do that. You need to send me a personal message (message member) and tell me what your email address is, then I can email you the spreadsheet as an attachment.

Norm

Colin Seggie, I have sent a reply to your PM and it will be in your inbox to see once you have logged in.

Thanks for your thoughts, and thank you George for pointing to the discussion back in August that I should have seen. I assume that TIR means "Total Indicated Runout"?

So the summary results from both threads (for TIR) converted to imperial are:

0.0005" new Indian

0.0009" 5yr old Chinese

0.0015" before overhaul (0.0005" after)

0.0024" dirty (0.06mm)

and I won't event attempt to list the one that has 0.3mm TIR, or the one that was visibly wobbly.

The good news is that I retested my chuck but using a piece of 1/2" precision ground MS. Now I get 0.0005 - 0.0010" so it seems to be performing OK. Using other random pieces of bar would give the good result or larger errors (0.0025" ) which could be fixed by very lightly tapping the high jaw before tightening.

I have also just realised that I should have slip stoned the edges of the reground faces on my jaws. They might be catching on different bar material? I will try this tomorrow.

Edited By JasonB on 17/09/2013 20:17:08

Would people like to submit figures for the actual run out found for their 3 jaw self-centring chuck? Insert a true piece of 5/8" (or 16mm) round bar and use a dial gauge to record the total deviation seen on the gauge (i.e. total deviation of 0.002" thus out of centre is 0.001" )  .

I ask this because I have no idea what is typical or the best achievable.

My Pratt 3 jaw chuck on my Myford was showing 0.0035" out (total) and not gripping properly because of wear at the jaw edges. So I have re-ground the jaw tips, in situ using paste on a bar between centres, and now the jaws grip perfectly along their full lengths (test with blue).

However, the total run out deviation now reads 0.0025" (i.e. it is holding a 1/2" rod 0.00125" off centre). Slightly better, but I expected it to be nearly perfect after the jaw tips regrind. What would you expect?

Edited By JasonB on 17/09/2013 14:25:12

I do apologise to all you MT3 people, but I agree with Gary. I am sure that the MT3 works fine in holding tooling but R8 holds and then lets go when you want it to.

Edited By Norman Lorton on 04/09/2013 21:40:31

Search also for "Honing bronze cylinder bores" in the search keyword box above as this topic was covered in January 2012.

I think I know where Ken is coming from as I had the same questions a couple of years ago. The question breaks down into getting a) an accurate bore of correct diameter, and b) a suitable surface finish. I would add a new variable in that striving for either the bore or finish can give an incorrect bore profile, especially a 'barrel' with a larger bore in the centre or a 'flare' with larger diameters at the outsides. I think this is the hardest error to correct for.

A reamer gives a good parallel bore of true diameter, up to perhaps 1" in non-professional hands, but the finish might be messy, as Ken says. I find that a flap of emery or wet and dry paper, held in a small wooden split stick, can produce excellent finishes, working from 200-1000 grit with plenty of paraffin or WD40 to wash away material. The job rotates in the lathe at a few hundred RPM and the stick is carefully moved in and out to avoid any creation of the barrel effect. Problem is it also enlarges the bore by 0.0005" or more.

Honing (using stones held on a frame) is obviously a superb technique in the professional machines described above as the bore is enlarged from its rough cut by a few thou and the finish of cross honing is perfect for cast iron rings in a cast iron bore, and parallelism is maintained. But, it is most suitable for bores of 2" diameter and upwards. I have seen sets of small hones at the ME Shows and wander what success people have had with them?

I did some web research and lapping (grinding paste on soft mandrels) is the described technique for getting accurate bores of suitable finish. I wanted to make some bronze bushes in which would run stainless pushers of diameter 0.8749 - 0.8750. The bushes were 1" long and the differential thermal coefficients of expansion (appx. 0.001" between stainless and bronze over 100 degC) meant careful measuring at a fixed temperature. I bored the bushes to 0.8735 - 0.8740 and then lapped them in the lathe using a home made mandrel with an aluminium body of nominal 0.8730 diameter and an end taper wedge to progressively enlarge it from the centre. The mandrel was designed to enlarge as a slight barrel, so as to counter the effect of it producing a 'flared' bore diameter increase in use. Diamond pastes, plus light oil, starting at 40 micron (400 grit) would remove a thou in 60 seconds. 14 and 5 micron then produced near polished surfaces. Absolutely thorough washing before measuring or changing pastes was essential.

Lapping this way produced bores that were so close in diameter to the stainless pushers that they were locked solid at 15 degC, just moved at 25 degC, and slid like glass at 35 degC. If it is an iron piston in an iron barrel one will not see this temperature effect.

I have no professional training but taught myself, so make a mandrel lap Ken and have a try! PM me for more if you wish as I have said far too much in this reply and will have bored too many.