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Member postings for Roger Hart

Here is a list of all the postings Roger Hart has made in our forums. Click on a thread name to jump to the thread.

Thread: What I did today
13/04/2014 07:44:42

@Bazyle

To confess, I broke the shaft whilst turning off the impeller (glued on). I was surprised it broke and the bits looked like no metal I had ever seen. Apparently ceramics are very common in pumps, I didn't know that.....

The ceramic shaft is not really long enough to put a grinder on anyway and would require retaining the inner stainless water chamber + bearings - inconvenient for mounting anyway. The ceramic shaft did have a small hole - about 1.5mm down the middle, if you are lucky you might glue some extension down there but it would not take much strain....

The ceramic shaft is pressed into the rotor and held by a stainless springy wrapper inside the rotor - I bashed out the stump (not too brutally) and the wrapper was still a bit tight for my 10mm silver steel replacement even though the ceramic shaft had been 'exactly' 10mm. So I slackened the springy wrapper whilst still inside the rotor using a 10mm reamer until the new shaft would squeeze in without too much force. My plan was to secure with epoxy if necessary but I have not found the need to do this.

Please heed warning about rotor being wrapped in stainless and having sharp edges.

12/04/2014 07:39:04

Well thank you all, I had not intended to stir things up so much. The motor runs about 1500rpm and rated about 100Watts and is OK for sharpening small drills, gravers etc - so you work from the front and likely to be out of line of fire in the unlikely event of a lump flying off. I can fit a small aloxite wheel but it is more trouble than it's worth - I use a conventional guarded grinder - with proper guides etc. Nevertheless something could go wrong and risk is always worth pointing out, I am certainly not pissed off with advice.

I have been tinkering for well over 60 years and worked in industry long before H&S was a big deal, people got hurt and little or no compo for it - you learned to look out for yourself and your mates. Most of my work now is on a 6mm watchmaker lathe or an ML10 (with looseish belts) and a 1940s sensitive drill and the worst I get (so far) is a (rare) whack on the knuckles from a chuck jaw or what is left of my hair caught in the drill belt and I do wear eyeshields when I feel nervous or the swarf flies about. So to all, stay safe, think 'what could go wrong', some of you use much bigger kit, a visit to A&E is very boring. Finally, the grinder in my first job was an old series motor and open wheel loosely screwed to the wall at face height - that was a bit scary.

11/04/2014 10:44:04

p1030089.jpgThis pump was noisy and Mrs R complained, the pump was slung in the back of the shed awaiting sentence.

A few bits from the junkbox and a silver steel shaft to replace the 10mm ceramic shaft and some ball races (ex junkbox). The inner stainless shield and ceramic bearings were discarded although the new shaft did run fairly ok in the ceramic bearings. A very handy little grinder, just needs a simple grinding rest now.

A warning though, the rotor is jacketed in stainless steel and has sharp edges - be careful, I found out the hard way.

Thread: How to polish hairspring?
03/12/2013 13:22:42

Thanks all for ideas. @DC - I had thought of using an inert atmosphere but quenching seemed a bit of a problem. @Niko - mmm, will think about that. @MG - Thanks very much for the Saunier link, I had remembered the conical former method but had forgotten the pegwood/cork block method. Tried it out with an upturned placemat and a pencil and diamantine - works very well and not all that difficult. Also your link is very impressive - that chap has some very nice kit.

Also checked out the bluing method (on earlier tryout) - used a brass block 6.25mm thick with a 1.5mm hole in the side for a thermocouple - cheap digital voltmeter type - then sat block on kitchen electric cooker and wound up the temperature (Mrs R not looking....). Once got to 340C turned down the power and looked carefully - voila a nice blue colour - grab with tweezers and wave in air - job done.

02/12/2013 16:21:20

Trying to make a hairspring for an escapement experiment - 0.1mm thick by 0.63mm wide 9 turns so about 13mm dia. Polished flat steel wire - OK. Coil 4 strands interleaved OK. Soap well to avoid scale, bring to red hot and quench OK. Seperate springs OK. But very hard to bring to a good polish before bluing. Outside coils can be done on a wooden cone but the inner face of the coils is 'very difficult'. Also made special tweezers lined with wood + diamantine - workable but have to be v. v. careful not to distort spring.

So ideas for polishing the hairspring please - or how was this done commercially - I cannot believe this was done by hand except in the very early days. Alternatively is there a really good way of tempering but keeping the polish? BTW, I know I can buy hairsprings - but making one seemed more fun - till now.

Thread: Jaws for Eclipse chuck
24/10/2013 09:49:26

To All,

Thanks for the advice. I epoxied the half-cut chuck to a piece of cut-out hardwood and added a brass shim in the first cut to help get a 90 degree cut for the second. Worked pretty well, a lot easier than the free-standing attempt. So I reckon Eclipse must have used some sort of jig to constrain the saw.

I seem to remember seeing a utube of a fountain pen knib being slit by a VERY thin saw and that was constrained by 'rollers' either side of the rotating blade.

21/10/2013 09:06:05

Attempting to make new jaws for an Eclipse 160 pin chuck. Essentially the jaw assembly is a 4mm stem drilled 2.5mm plus a biconical jaw about 6mm dia in one piece of hard(ish) steel. My problem is slitting the jaws - the stem tends to bend under the saw pressure despite very gentle progress and it is very difficult to get the saw to run exactly along the centre line. The slit runs down through the jaws and about 5mm along the stem. My next attempt will glue the jaw assembly to some hardwood for support but surely Eclipse had an easy production technique - what?

Thread: Lathe motor popping
02/03/2011 07:55:38
Sounds like you have this sorted. I had this problem and found it was caused by an arc tracking across the mica insulation of the centrifugal starting switch to earth. Probably due to muck/dust having accumulated. Once this problem is established it is hard to fix because it is not easy to replace the insulation. Eventually the problem gets bad enough to pop the earth leakage trip an annoying number of times.....
 
I fixed mine by running the motor through a BIG isolation transformer.
 
Roger H
 

Thread: Radiused knurling
05/11/2010 08:14:32
Thanks to John and Michael.  In the end I bought a clamp type knurling tool and modified the toolpost to a 1/2 inch round.  Mounted in my spherical attachment (MEW design).  Rounded the sides of my terminal screws then knurled.  Results are pretty good tho not exhibition quality - but this was a one-off.
 
If I wanted a really good job on a tighter radiusI might try John's technique - but for average terminals I reckon the first technique can be persuaded to work OK.
Thread: verge escapement
17/10/2010 07:33:23
I have done 2 of these.  First set the verge leaves to be equiangled about the foliot or balance wheel pin.  Next adjust the balance spring so the foliot or balance sits halfway when in the movement.  Then set the escape wheel a little way out from the verge leaves and try gently with your finger,  advance the escape wheel to improve the action.  Adjust the lateral position of the escape wheel to achieve the best (least worse) beat.  Assemble and try.  Repeat as required - I found it a pretty frustrating business on verge watches.
 
What seems important is to make sure the acting faces of the verge leaves are a flat mirror polish - without this you are wasting your time.  If you are making the verge staff then some careful grinding of the verge leaf tips may be needed - but keep them polished. 
Thread: Radiused knurling
13/10/2010 12:20:35
I'm making some 'telegraph' pattern binding posts for a spark coil.  Old style terminals had a straight knurl on the terminal head that was radiused for good looks and ease of use.  How is this done?  Do I use a normal flat-straight knurl and round with a form tool or are there radiused knurls available - about 3mm radius say.
 
My current knurl kit does not have enough 'bite' to leave sufficient knurl depth for the post-knurl form tool idea to be viable.
Thread: How to accurately bore a milling spindle on an old lathe
21/08/2010 07:19:06
Thanks to all.  Clamped block to lathe bed and did final cut using the spindle's own bearings then used taper reamer pressed in by a flat-ended tailstock.  Worked very well,  max runout about 0.5 thou.  One problem.  Found taper reamer had cut a little too deep and had to machine 1/4 inch off the nose - lucky I had made this a bit long anyway.  I have used John's technique in past and that can work well too.
 
Roger
12/08/2010 16:15:38
I am making a milling spindle (2 inch block+2 taper rollers+centre-turned shaft) and wish to bore the shaft Morse Taper 2.  My lathe is a pretty old flat-belt job and I want the taper as true to the taper roller CL as possible (and not wobbly either).
 
Am I better off boring the taper in the 4 jaw (set true as well as possible) or would I be better off setting up the roughly bored M2 taper in the milling spindle as a sort of pseudo-chuck using its own block and taper roller bearings and pulley and then finish boring it??
 
Oh,  and not spending money either!
 
Roger H
Thread: Low rev. dynamo
13/06/2010 15:02:42
I too like the Honda generator!
 
As a design guide in 1902 the book says:- "In large machines,  carefully wound, an efficiency of 1 volt per foot of effective wire on the armature at a circumferential rate of 1250 feet/min has been obtained, but, as has been stated, 1 volt per yard is what may be expected from small machines".
 
Plus ca change...
10/06/2010 15:37:28
Hi Johan,  The problem is the low revs/min.  From my old "Dynamos & Electric Motors" book of 1902 I reckon you need an armature about 120mm dia and 100mm long to get the sort of power you seek from a conventional dc dynamo at say 500rpm.  Designs of the period are the Manchester design or the Siemens design.  You might look at the generators used for wind generators - static coils and rotating magnets - plenty of homebrew designs on the web.  The result is low frequency ac though.  Very impressive engine!
Thread: Diesel engine
27/04/2010 16:19:42
Hi Jason and Anthony
 
Thanks for the links.  I checked out the hot bulb engines - beautiful - just what I had in mind.  The horizontal engine looks a lot like a Wyvern.
 
I may get the Dux info for a look at a more modern design.  Meanwhile I have to complete Dave Parkes' 2 stroke job.
 
Thanks again.
Roger H
25/04/2010 17:58:28
I have read ME off and on for many years but a cannot remember seeing a design for a diesel engine of the hot-bulb/injector or injector type.  Fuel to be conventional automobile diesel or possibly paraffin.
 
Is this a practical proposition?  Has it been done in model size?
 
Roger H
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