Member postings for Simon Williams 3

We had house rabbits through the winter as children circa 1970. They lived outside through the summer, but it was cold and nasty out there in the winter. For some reason they loved biting through live cables of stuff round the house, and I got several significant wallops off the mains checking for faulty cables. Including one very nasty experience with one hand earthed, the other hand found the exposed live. But I've lived to tell the tale.

Never did solve the riddle how a rabbit can bite through a live wire without apparent damage (to the rabbit) and not learn the error of its ways.

As Brian says, for some reason they seemed to find biting cables irresistible.

Hope your earth leakage trip is working...….

Best rgds Simon

(Don't tell anyone I was mad enough to suggest this, but a diamond disc in the angle grinder will shape the tungsten carbide tool.)

It's a bit rough and ready and will need stoning up with a diamond file afterwards, but it can be done.

Keep up the good work, thanks for the photo's

Simon

Ron - good evening,

Good to hear you've decided to buy the tool and have a go, and not so good that you've found the left hand pitfall. Obviously running the tool backwards isn't an option - the mandrel on which the head is mounted is screwed in with a right hand thread so running the tool backwards will simply unscrew the thread.

I never thought of running the tool bottom to top - how do you adjust the diameter with the tool below the work using the radial hole? Maybe it's just keyhole surgery?

I feel it's a bit unfair to criticise the tool supplier for not including at least one left handed tool in the kit. You're into advanced boring head using, and fettling a suitable tool is an exercise for the student. I dare say most purchasers of one of these boring head kits of tools would send the left hand tool back saying it's been made wrongly!

Good luck and do let us know how it goes, Would love to see a video - or at least some piccy's of work in progress, ideally with a view of how the tool is sharpened ant presented to the work piece.

Simon

And I meant to say please be sure that the packing pieces at the outer end of the two toe clamps holding the work in place are positively located to the clamp plates. They are at the periphery of the faceplate, so encounter the maximum bursting forces, and moreover if one of them does shift you're in trouble straightaway. So I wouldn't rely on the clamp force reaction/friction to hold these from spinning off the faceplate.

Best rgds Simon

Well, safe it ain't, but serviceable - yes. I'm with you I don't like the bits sticking out beyond the periphery of the faceplate, but given that the workpiece is the size it is it don't make no never mind whether you've got one bit sticking over the edge or three. However for no better reason than to calm my nerves I'd be slightly happier if the counterweight bolt was head visible not tail visible. Anything to reduce the pokey sticky out bits.

Which brings me to the first rule of face plate work

Don't get your finger in the mangle.

Second rule is don't get anything else in the mangle either (hair, beard, sleeve, watchstrap, wedding ring etc etc.....)

Seriously though, 300 rpm - which isn't a lot if you're only drilling the pilot hole - is still enough you can't see the catch points, so you have to remember not to get close enough to get caught. It sounds obvious but make a conscious decision where the limits of the no go area are while the work is stationary and before turning if on.

Make no sudden movements - ask yourself all the time "am I still outside the danger zone if I make this next movement"? It goes without saying you must roll the work through a few revolutions to be sure nothing fouls THROUGHOUT THE LIMITS OF MOVEMENT OF THE TOOL. I find it useful to clamp a bed stop in position to stop the saddle getting too close to the headstock and potentially contacting the rotating work.

How are you going to deal with the situation where it all goes horribly wrong. Can you reach the OFF button without crossing the zone of flying debris? A footbrake is a comforting feature suddenly. Can you bring the situation back under control whilst staying right of the saddle?

Faceplate work like this gives me the heebie jeebies. If anything does shift it'll go to hell in a handcart before you can say oops. But it's very effective way of getting an accurately sized hole square to the surface.

I like Emgee's suggestion of two additional plates clamped on a diameter at right angles to the long axis of the work to be positive stops. As they are on a diameter they won't introduce an out of balance moment.

Make sure your fixings are not only tight but also clamp solid metal, you'll be fine.

Good luck Simon

PS Did I say keep your fingers out of the mangle?

Good evening all, and thanks to Neil for flying this kite, and in response I'd like to offer a very personal and skewed view of what I want to see at an exhibition.

I went to the Midlands show on the Sunday. I was surprised how quiet it was given the number of cars in the car park. Bristol, earlier in the year, was busier, though I went on the Saturday so I'm not comparing like for like. I haven't tried Doncaster, and the last time I went to Ally Pally I was defeated by the crush. It was like a jumble sale at closing time.

The perennial issues over attracting footfall, and the reliance on the same faithful members to carry the burden of making it happen, are not peculiar to our model activities. I volunteer at a number of village events, it's the same microcosm wherever you look. I'm prepared to accept at face value the proposition that these shows are not a licence to print money, and showing me "honest accounts" - fascinating that it might be - won't show the added value of all those volunteers.

I'd like to see all traders at no charge to attend. They're what the organisers are selling, and the idea that they are an income stream to be milked is short sighted and false. Let them make a profit if they can, it's a rough world out there and it's killing the golden goose to squeeze them dry.

Ditto accredited clubs. Their exhibits are what the show is about, though (heresy that it is) there are too many of them. I'm suffering museum fade after the first dozen, though I recognise that my dozen will be different from someone else's. But if you offer free display space to traders then the Clubs are going to want the same deal. However I want to see people who made the clever stuff on show, and to be able to talk to them and shoot the breeze. That personal interaction is why I go to a show.

If the organisers are going to make those two decisions then the gate price has to go up, significantly. I don't know how much, but bring on the "honest accounts" and a business model will reveal itself. To do this the footfall has to be reliable, and as the source of income the higher the better. Bring on free parking, reasonably priced refreshments and a suitable location. Increasing the entrance price is the cost of keeping these shows alive. I take the points made above how the parsimonious nature of the clientele is killing the very activity we support, and unlocking this conundrum is the key to turning it around.

So I would love to see a wider interest served by the show than just steam, shiny bits of metal, and bacon butties. Why does my wife not want to go? Musing on the contents of the "What did you do today" thread, we're into Arduinos, old fashioned discrete electronics, stepper motors, properties of materials etc etc. I'd love to see the cross pollination of ideas into radio control, electronic test equipment, machined wood work (which seems to be very popular) and practical demo's of stuff. Which MyTimeMedia mag's sell well? The gas turbine guys - with shiny exotic materials, loud noises and a distinct hint of danger - open a window of opportunity and "I fancy having a crack at that" to every show I've been to.

But Warwick as a venue isn't big enough.

Every year my wife takes me (!) to the NEC for the Festival of Quilts. Which grows, year on year, and this year occupied four halls of the NEC. You cannot get round it in one day. Don't start me on the subject of ladies of a certain girth on electric scooters, but the point is that the practical exuberance of expressing our creativity is alive and well on the distaff side - and not a few men as well. Taking this lesson back to our model engineering and associative activities I'd like to suggest that Uttoxeter racecourse is more of the scale of the event we should be seeking. I've been to the antiques fair on the Bath and West Showground - 5 acres of it - if we want our show to persevere though the vicissitudes of rising costs and falling expertise we need to broaden its appeal, not constrain our horizons to those of the local village hall.

So who's going to take the lead?

Rgds to all

Simon

edited for typos

Edited By Simon Williams 3 on 27/10/2018 00:35:56

Good evening Sam,

I asked myself the same question - albeit for different reasons - a little while ago, as I was trying to calibrate a battery condition meter (volt meter) to give some meaningful indication of the state of charge of lorry batteries I use to run PA amplifiers for a local fete. While they are running the PA they have no charge connected to them as they are in the middle of a field, so I wanted to know what the relationship between terminal voltage and state of charge was.

It's not a simple question, and I'm sure others will chip in with chapter and verse. but I found this which seemed to make sense.

http://scubaengineer.com/documents/lead_acid_battery_charging_graphs.pdf

I think if you follow the graphs on the pages labelled 67 and 68, which show terminal voltage against charge and discharge currents, you can relate the difference in terminal voltage for a given state of charge to the current into or out of the battery.

HTH Simon

Edited - apologies, I'd linked to the Google page not the specific file/webpage.  Hopefully fixed.

Edited By Simon Williams 3 on 25/10/2018 22:50:21

Morning All,

My suggestion of needing to be able to run at 20 or 30 rpm comes from having done exactly the same job myself, using a Rong Fu drill mill. By the time I got to 75 mm diameter running the cutter at a "proper" speed I'd got all the chatter in the world going on, so reducing the speed significantly is one way of reducing this to give a good enough surface finish to hold that tolerance of a couple of thou. I just wanted the biggest hole I could cut in a steel flywheel as part of a home made wood chipper, I got to 100 mm dia eventually but it was on the absolute limit of my capabilities. I wasn't bothered about hole tolerance, it was a clearance hole for the chips to go through, but I did want it to look pretty. Incidentally I cut two of them, as the flywheel had to balance (approximately!)

The mill drill has its limitations, but it is big and heavy (for the size of machine) and it will run slowly with lots of torque. No offence to the SX machine, but I've got me doubts.

I forgot to note that the boring tool used in the head axially is a right handed tool, but the tool needed for the radial position is a left handed tool, as it cuts on the opposite edge.

I'm afraid I'm responsible for putting Ron off having a go. My apologies for being such a doubting Thomas, by all means have a go but approach with circumspection!

I've also drilled holes in one inch steel plate with a hole saw. They will do it, but we mounted the work on the table of a big vertical mill with flood coolant and went very slowly with frequent withdrawals. That was a 40 mm hole, not sure that much larger is viable as the saw is too flexible.

Best rgds Simon

Hi Andrew, if that's aimed at me you are quite right to raise the question. I reckon my ability with an internal mic' at 4 ins diam is probably only +/- 1 or possibly 2 thou, so we're on the knockings of the specified accuracy anyway. Always assuming that my secondhand internal micrometer reads true (of which "true" is a whole new can o'Worms). I've got a suitably sized ball bearing we can use the OD as a putative standard and a 4 inch external mic' as corroborative evidence. What's the ISO 9001 speak for "somewhere handy"?

(I was tempted to answer with something facetious about using a digital Vernier, but I thought I'd better not).

Best Rgds Simon

Hummmmmm

Thanks for your quick reply Ron, not sure how to break the news to you, and I'd be grateful if Jason and or Neil would chip in, but I think you are beyond the realms of SX2P capabilities, and stand a good chance of wrecking the motor/drive. You're going to be running the machine at bottom speed for an indefinite amount of time, and, from what I've read on this site, this is territory where these machines are not happy. Having said that I have no direct experience of this range of machines, so if someone wants to say I'm talking nonsense please do!

However, sorry to be the party pooper, but that's just the first problem.

The good news is that you are looking at cutting ally. At least that lets you push the cutting speed up towards the capabilities of the machine.

However I do worry about your wish to make a set size to a couple of thou. My experience of trying to set one of these boring heads to a given size is that they are lip service to the idea of boring rather than walking the talk. I have two ostensibly the same, but they are made differently and it makes a big big difference to the serviceability of the head. I estimate that the repeatability of setting is about +/- 10 thou, or 0.25 mm, you are going to struggle to hit a size to a couple of thou. One of the heads I have here has a captive gib built into the dovetail, I can set that to about +/- 5 thou, the other is the really cheap and nasty version, it looks the same but there is no gib and the setting screws bear on the side of the dove tail. On a good day with patience I can set this to about +/- 20 thou! It's rubbish! Hopefully Arc' don't sell these!

As you say, by all means try it and see how you get on, but be sceptical about the carbide tools you get as part of the kit. They look pretty enough, but to get good results the cutting edge needs to be at the centre height of the hole - in other words the point of contact of the cutting edge must be on a diameter of the hole. Some of these tools are made wrongly - the tool is located in the head on a diameter of the head, so the top face of the cutting edge needs to be BELOW the centre line of the tool, so that when it is mounted in the boring head you can twist the tool to give some top rake and bring the cutting edge up to the centre line. If the tool is too thick tilting the tool to give some rake pushes the top face of the tool way too high, and the cutting edge is actually trying to cut with negative rake. You won't get good results with this situation, even in aluminium.

Having been a douche of cold water, what about a more positive approach? Where are you in the country? If you fancy a trip to West Gloucestershire I'm pretty confident that my faithful Centec will stand a good chance, though of preference I'd stick it in the lathe and bore it out the old fashioned way. What's the overall size of the part? and the dimension of the hole centre to the furthest edge/corner?

Best of luck, Simon

Ron, good evening to you.

At risk of asking a whole lot of questions you may have already addressed:

(1) What are you going to turn said boring head with? (Question of sufficient torque to cut material at 50 mm radius)

(2) What material are you cutting (same question as (1))

(3) What tolerance can you accept on the nominal finished diameter of 100 mm?

(4) How good (rigid and repeatable) is your boring head?

I've played this game, and (as Neil says - I paraphrase) you could die of caffeine poisoning waiting to get to the finished size, my experience with holes this big is that it is very difficult not to end up with chatter at the tool, which in turn jeopardises your ability to hit a given size. I also found that it was all too easy to stall the cutter in the work, which of course chips the edge.

Using a carbide tool solved some of the surface speed problems I encountered trying to do the job with a HSS cutter, but then it is a lot more difficult to adjust the cutter geometry than with HSS.

The reason for querying the quality of the boring head you envisage using is that you gets wot you pays for in terms of rigidity and settability (if that's a word).

If you've got a socking great milling machine which will run at a suitably low speed (say about 20 rpm for HSS) and a nice Wohlhaupter boring head then I'll wind me neck back in. If you've got a mini mill and a Chinese £20 boring head, well......

Look forward to hearing you've managed it.

Simon

+1 from me for Sifbronze, though silver solder will also work, but not always. It seems there are some grades of carbide the flux won't wet, so the solder/braze won't run on to the insert. You just have to find a different grade of insert, though it might now be possible to use some of the more active fluxes and get a better result with these difficult examples. I've only tried doing this with J & M easyflo no 1 which is a pretty benign flux, and intolerant of dirt or funny oxides, so it isn't 100% guaranteed to work. I don't know the science behind this but you can certainly get good adhesion with most insert materials. If it works at all it'll be a good job.

I'm guessing, though I haven't tried the experiment, that coated inserts may also cause problems in getting the flux to wet them.

Absolute Beginner :

I simply can't accept that there are grounds for believing J B Tools are messing you about, it's not credible. I've got no connection with them other than as a satisfied customer of many years standing, and have always found Jenny and her husband absolutely delightful to deal with. This is a simple oversight or an email has got lost (it happens!).

Can I suggest someone brings this to the attention of Jenny tomorrow at the show - I know she'll want to sort it urgently. I'd do it myself but I'm not planning to go 'til Sunday.

Can't speak highly enough of them.

Rgds Simon

I agree with all of the above, what a piece of work!. I'm left with admiration for the inventiveness and diligence that saw the project through to its conclusion, but also with an enormous question.

HOW?

Not how was it done, that was magic, nor even how did it happen that the completed gismo did what it set out to do, but how on earth did the magician find the time and resources to see this to its conclusion?

I've had two episodes of being self employed,, and I learned very quickly to say the Lord's Prayer before getting out of bed each morning. Give us this day our daily bread; making things is all very appetising but it doesn't pay the mortgage until you sold it and moreover collected the debt.

So either I'm missing something, or Jesse Beecher knows something I don't. Well, actually it's pretty obvious that he knows a whole lot of stuff that I don't. But HOW does the author of this manage to fund the resources to see something as downright jolly clever as this to fruition?

I looked through the video, and said to myself "there's a year's work in that". £20K isn't enough.

HOW?

Rgds to all Simon

I held off offering to make a gear for you as I read it that the "I fixed it" factor was part of the entertainment value here. But I'm W Gloucestershire if that helps, and although I haven't checked there is a 43 tooth circle on my dividing head I'm pretty sure there is. If it helps to rattle one out I'm game.

Simon

Edited By Simon Williams 3 on 09/10/2018 18:00:10

So the problem becomes "how to mark out 86 divisions around the circumference of a 44 mm gear blank".

My Boys Own Dividers method wont work, because half of 86 is 43, which is a prime number. So resort to the paper and triangle method. You've mentioned "turning up a blank" so I assume you have a lathe, therefore a chuck, though any disc of known diameter will do.

Assume for the sake of simplicity that the OD of the chuck is 100 mm. Then the circumference will be 314.2 mm. This doesn't divide neatly into 86 equal portions of any simple size, so take a piece of A3 paper and draw a line 315 mm long. This allows a smidgeon for the thickness of the paper. At one end draw a line 292.7 mm long at right angles to the first. Make the right angle as accurate as you can. Now join the two ends to make a hypotenuse 430 mm long.

430 mm divides nicely into 86 times 5 mm. Mark these divisions along the hypotenuse.

Now drop parallel lines from each mark on the hypotenuse to the 315 mm line. There will be 86 lines marking out the length of the circumference of the chuck. Cut out the 315 mm line, now divided into 86 equal increments, and stick it to the periphery of the chuck. Rig up a pointer as an index, mark out the 86 teeth on the gear blank.

I'm betting Jason's drawn a drawing to explain in the time I've tried to explain.

HTH Simon

Bit of an OOPS!.  You need 87 divisions because the first and the last will be overlapping.  Otherwise the arithmetic is valid in principle, though wrong in practice.  Sounds like the comments I got in my last maths exam!

Edited By Simon Williams 3 on 09/10/2018 16:58:39

'ang on ang on ang on!

If Jason has it right, and I'm pretty sure he has, then the gear you are aiming for is 86 teeth at 0.5 module, the OD of the blank is 44 mm. My calculation was based around the number of teeth being fixed, but now we have a dimension for the centre to centre distance that changes everything.

Centre to centre distance = mod x (n1 + n2)/2 where n1 and n2 are the tooth counts of the two gears. I take it that Jason has used this to calculate n2.

I suggest we need to be sure of the centre distance - everything depends on that.

edit - Jason can draw pictures faster 'n I can type

Edited By Simon Williams 3 on 09/10/2018 16:23:27

Let's do a bit of arithmetic.

45 mm is 1.772 ins. DP of a gear = (n+2)/OD, so DP = 72/1.772 = 40.64.

That's a bit fishy not to come out (closer to) to a recognisably whole number, so convert to module and see if the answer is more comfortable.

Module = 25.4/DP so mod = 25.4/40.64 = 0.625 which isn't a "standard" number either.

Since I started this the picture above arrived, given the age I'd rather believe in DP science than module. 40 DP would be a recognisably standard number, would you like to check the OD of the blank carefully and see if 45 mm could be comfortably 1.800 inches/45.7 mm? I'd hate to think you went to all that trouble to make a gear which turned out to be a little bit too small!

And while we're at it, could you please advise why 70 teeth? If the 45 mm blank carried 69 teeth it would be 40.07 DP which I could believe was as close to 40 DP as one might expect to measure. Mind, dividing the circle up into 69 by eye is going to be more difficult!

Best rgds Simon

Edit - Jason's beaten me to it (again!)

Edited By Simon Williams 3 on 09/10/2018 15:51:16

Dividing a circle into 70 shouldn't be beyond the wit of a man with a sharp pair of spring dividers and good eyesight (or a magnifying glass). Oh, and a steel rule.

Assuming the gear blank face can be marked, first divide it into seven. The key here is that if you set the dividers to 0.439 times the diameter of the blank you will divide the circle into seven chords. Mark off the seven chords, making sure that the last chord steps back exactly to the starting point of the first.

Incidentally the figure of 0.439 comes from this:

Seven chords in a circle each subtend 51.42 degrees at the centre. Length of a chord of a circle = 2 sin a/2 where a is the angle subtended by the chord.

(Or you can look it up in Machinerys Handbook under Circles - lengths of chords for dividing))

So back at our gear blank, divide each seventh in half. You could divide the original circle into 14, but the bigger the starting sector the more accurate it will be. Examine each halfway - seventh to make sure they are all equal. At this point mark the fourteen divisions on the periphery of the gear blank with a couple of strokes of a three square needle file.

You could guess what happens next. With the needle file, mark five subdivisions in each fourteenth of the periphery of the gear blank. I reckon a practiced eye could get these evenly spaced around the periphery to an acceptable accuracy, whatever that means.

You've now got the position of the teeth - all 70 of 'em - marked on the blank. File to shape. Easily said!

However I'm not entirely sure about the original dimensions, but for the sake of keeping this post to a reasonable length I'll post that separately.

I'm with Andrew, I'm in favour of increasing the number of posts to qualify for member benefits. And I like Neil's policy of being vague about what this minimum number is.

However, if I've understood Neil's comments correctly Nicole Curtis has managed to post a reply to a classified ad' without being qualified to do so. So that begs the question of how he/she/it (we don't know!) has managed to bypass this safe guard. No point in increasing the shield if there is a way round it.

It never fails to astonish me the time and effort some will put into being dishonest, when for less effort they could apply their talents to making the world a better place.

Simon