Member postings for Simon Williams 3

I swapped the original two speed motor on the Bantam 2000 I bought for a single phase motor, hated it. Every start was an adventure, nasty sudden bang on the headstock gears which made me cringe. No clutch on a Bantam, so threading with a tap or die was always an adventure.

So I changed to a 3 phase 4 pole motor (ie single speed) and rewired the controls so that the speed change switch operated the VSD to run at 100 Hz. Obviously that frequency is controllable, but that's a nicety.

With a three phase motor on a VSD comes soft start, DC braking stop, and controllable frequency. With the range of geared speeds on a Bantam playing with the frequency is an option I use very seldom, though it does let me run at very slow speeds if I'm doing something large or chattery.

I have also fitted a 2 pole three phase motor to a Myford S7, this gets the speed up well but you don't really need this with a Bantam where the option for 1600 or 2000 revs is built in. I'm more concerned about using the Bantam with the motor at or close to its normal operating parameters for best power efficiency for operation with carbide tooling so I believe the 4 pole motor is the way to go, particularly as the motor I fitted at 1.1 Kw is a bit underpowered and objects to operating at the highest speed at 100 Hz. Effectively I've forfeited the top speed of 2000 rpm but it's otherwise a lovely machine to use and I'm mighty pleased with it.

HTH Simon

An ML1, bought for £37.50 in about 1970. Gave that away long since. Then an ancient (1953) but serviceable S7 I paid £400 for in about 1975, out of Stroud Tech College on the most horrible angle iron stand you're glad you never saw. Scrapped the stand and made a workbench on which the S7 still sits, getting on for 45 years later. My Dad had it in his workshop almost till he died, Can't quite bring myself to part with it, It's an old friend!

Then I bought a Colchester Triumph circa 1940 off a farmer's son in Tewkesbury. This was the old wrought iron stand version and was a slow old rumbling machine but I loved it. All geared head, swing of about 7 inches, ran it off a three phase converter I borrowed. With a big 4 jaw chuck I did all sorts of work with this but sold it when we moved house shortly after getting married in 1985. Actually sold it to my then next door neighbour, who was into model engineering (steam/rail) semi-professionally, and wanted it to make flywheels etc. We trundled it across the road on a pallet truck into his garage; for all I know it's still there.

Somewhere in this sequence I was given a Holzapffel clock maker's lathe, treadle operated, been stored in a damp greenhouse so it was suffering a bit. Gave it away about 20 years later to another (different ) neighbour who fancied a restoration job. He's died since, no idea what happened to the lathe which I regret getting rid of. Pretty thing, all dovetails and curved handles. No idea how to use it though.

In 1997 or thereabouts I decided that my ancient but trusty S7 was due for replacement, I bought a Colchester Bantam 2000 Mk2, fully geared etc, runs off a three phase VSD. Super tool, hardly touched the S7 since though I can't quite bring myself to sell it on, even though I could do with the room. Been squirrelling accessories for the Bantam for 15 years or so, can't get enough add ons.

Still haven't sold the S7, it's now got a gearbox fitted and gets used for taper turning and metric threading.

Rgds to all

Simon

Duncan -

My slotter is presently set up to cut the key ways in some myford changewheels I made, so if you would like to send me the blank I'll cut the keyway in it and post it back.

PM me if you are interested.

Rgds Simon

If you are short of head room, two suggestions:

1 Do it the old fashioned way with a dial indicator clamped to the quill, i.e. get rid of the drill chuck.

2 I hold the spigot of the centering indicator in a collet up the quill taper to save forfeiting several inches of head room. In my case the collet is MT2 but it means the top of the centering indicator is right tight under the nose of the quill.

I guess the accuracy of the centre isn't crucial to a few thou' so use a sticky pin in stead of the DTI.

HTH Simon

Continuing the theme, though it's taken me a little while to find the thread, here are some pictures of my repair to the bronze bearing located in the quill assembly supporting the driven pulley. The pulley is cantilevered above the bearing, so the belt drive forces pull the pulley sideways. In my case the inner of the bronze bush wasn't too bad, but the sleeve which runs in it and which carries the spindle drive key was badly scored and wasn't something I thought I could re-make. I thought at the time that this was the cause of a horrid rattle coming from the drive, but (as explained below) this was a mis-diagnosis.

Anyway, here is a link to the pictures I took of my decision to swap the bronze bush for a pair of needle roller bearing, with proprietary hardened inner sleeve supporting the drive key bush. I've done a lot of work with it since, and it's not missed a beat.

Driven pulley bearing mod'n

You will also see there is some additional stuff about repairing the knadgered motor shaft.

Good luck with your new toy, and I'm sure I'm not the only one interested in how you get on.

Best rgd Simon

Good morning and thank you for the update. As a "Senior" citizen myself - and also with a Light Vertical - I look forward to hearing how you get on with this project. Hopefully you will be able to add some photo's to augment the saga.

You may be aware that there is a similar thread going on

Light Vertical Mill Restoration

Good luck with the project,

Best rgds simon

To answer this "sub-question" - yes I can very definitely recommend JB Cutting Tools, Jenny and her husband are two if the nicest people you could wish to meet and will see you right. Usual disclaimer. I've dealt with them for years at the various shows and I always look forward to meeting them.

But I suggest you need to ring her up and describe what you want to do, as the usual choice of inserted tools may not serve you well. Many carbide tools/inserts are intended for use with effectively unlimited power and a rigid machine, it sounds as if this may not be the case in your circumstance. Jenny has a range of inserts for just the application you describe but they may not be obvious on her website. I think you want the extra sharp ones with no chip breaker.

There are many insert holders on the 'net, and no they are not all created equal. Buying stuff off ebay is fraught with peril, it's such a specialised bit of expertise and the descriptions can be misleading even when they aren't supposed to be. So it's time to phone a friend AND ask an expert. I'm sure Jenny will be pleased to hear from you.

A second option is to find someone who will return your existing HSS tools to something you can hone and keep sharp. I'm up for that though I'm in West Gloucestershire so we can do it by post. If you want to pursue this send me a PM and we can take it further.

Best rgds Simon

John - hope the recovery is still on track.

Where are you, (postcode) maybe one of us with more information as to how this should work can assist hands-on?

Rgds Simon (West Gloucestershire, GL17)

If you want to drill two holes which are truly independent of each other, drill one left hand and the other right hand.

Because the left hand never knows what the right hand is doing

Hoard them carefully, and wait for the day you need to drill out a broken off bolt in something completely irreplaceable. They are absolutely brilliant at catching the remnant bolt, at which point it unscrews itself out of the blind hole like magic. Better than an easi-out any day.

Don't use them in a keyless chuck - many such won't hold in reverse. A keyed chuck (generally) will.

Rgds Simon

Edit - MichaelG types faster than I.

Edited By Simon Williams 3 on 25/05/2019 10:08:40

So, (at risk of teaching my grandmother) to bottom out the one start/two start debate:

With a Sharpie follow the crest of the thread around the undamaged bit for one full turn. As you come back round it will be completely obvious whether you are one thread or two threads (or more!) along the work.

HTH Simon

Am I right in thinking those tool dimensions are right for a single start thread, but need modifying for a two start thread?

If this is a two start thread, the thread depth and width will be halved?

Rgds Simon

"Earth Engine operates on the same principle as the ‘Slingshot Effect’ space travel phenomenon," (Quote taken from their web site, link above).

Which would be fine, except the sling shot effect to which they refer does NOT violate the Law of Conservation of Momentum, nor Energy. So much for that explanation!

And the fact that this has absolutely zilch to do with the hypothetical existence of a magnetic monopole simply compounds the felony.

At least snake oil might have had a placebo effect.

Rgds Simon

Pilot hole is always a good idea, needs to be 1/3 to 1/2 of next drill size, not more. Give the next drill something to do or it will grab.

Drilling down a pilot hole in cast iron always needs the drill rake modified to be nearly neutral, a standard drill grind will always grab and chatter or rip the corners off the drill. Same goes for green brass. Standard 118 deg point jobber drill perfectly OK for CI if the rake is backed off. Negative rake not necessary, neutral or about +5 deg is OK.

Speed - 1000 revs is too fast as others have said. Drilling cast iron keep the speed low and the drill cutting. Chips should come out as discrete pieces - say half the size of a match head - not dust. Slowness not critical; to success (that's in the grind of the drill) but suggest anywhere below 500 rpm for 10 mm hole is right ball park. Slower the better, keep the feed going.

If drill wanders and chatters on entering the pilot hole (leaving a nasty serrated edge as it throws the work piece around) fold up a small scrap of rag (old jeans ideal) and wedge it in the pilot so the advancing drill touches it first. This is sacrificial, but will stop the chatter and grab as the next stage drill edge meets the face of the work.

HTH Simon

This seems to substantiate the Law of Ladies Underwear.

"The less you want the more it costs"

Simon

I've done some experimenting with telescopic gauges to see how accurate I am with them, and although it's not terribly scientific (I'm not working in a metrology lab with the resources to arbitrate on measurements to tenths of a thou) I would offer the following.

Firstly I measured a bore of about three inches with an internal micrometer. I could do this to a repeatability of about +/- 2 - 3 thou, as my ability to apply the same force to the micrometer barrel consistently was the limiting factor, though getting the micrometer straight across a diameter of the bore was also fiddly and variable. Taking successive measurements just taught me that I was a hopeless case and wasn't getting better.

I then tried telescopic gauges, in my case the Moore and Wright ones, though I do have some Starrett ones.

I found my measurement was immediately at least as repeatable, and with practice I got better in that the measurement I made with an external micrometer was also about +/- 2 thou repeatability initially, but I got better with practice which I didn't with the internal micrometer.. As the process of making a measurement with a telescopic gauge means making two measurements - one to set the gauge to the bore and another to measure the distance across that gauge - there is scope for more variation than a direct measurement. But using the telescopic gauge was more repeatable than the internal micrometer - at least in my hands. After some practice (I was boring a hole for a bearing) I was fairly confident my bore measurement was repeatable to about +/- 0.5 thou. Some of my gauges are in better nick than others, and it also depends to some extent on being well within the working range of the gauge, but that just taught me to be careful that my telescopic gauge was working properly.

Measuring the same bore with a digital caliper is revealing - the caliper may have a resolution of 1 thou but it sure ain't that repeatable.

I also have tried the same experiment with smaller holes within the range of a Starrett internal micrometer of the caliper kind (model 700) and find this is more repeatable, typically +/0.5 thou or may be a bit better, but of course this only measures the mouth of the hole and says nothing about the bore.

I've been careful to talk about repeatability, as I don't have anything I could actually say was calibrated to give an absolute accuracy.

HTH Simon

About this root 3 business, it depends on whether the line voltage (230V) is a line to line or a line to neutral figure.

To calculate the power drawn by a three phase motor load supplied with three phase 400 volts (line to line inferred) you need the root three factor. If the 230 volts figure is the same - line to line - then it follows that the root three factor is still needed.

If the supply is specified as 230 volts line to neutral then the root three factor has already been applied by dint of getting from 400 volts to 230 volts.

In each case the convention is that the line current in one phase is specified, and the other two phases carry nominally equal currents.

The confusion arises because while it is obvious that a single phase input/three phase output VSD is supplied with 230 volts line to neutral, to develop full power at the motor it generates three phase 230 volts line to line, not line to neutral. The motor rating plate assumes that the delta connected motor will be supplied with three phase 230 volts, just as the star connected motor requires 400 volts line to line to develop full power.

Of course the arithmetic changes with phase coverters that can generate 400 volts line to line three phase from 230 volts line to neutral single phase input.

HTH Simon

Hi Paul, this comes up every so often, and the perceived wisdom seems to be brick cleaner from your local builders merchant. I've tried it and it works a treat. Buy the one that actually says it contains citric acid, other formulations exist.

Good luck Simon

Let's do a bit of arithmetic.

I've got a bandsaw I bought second hand recently, I've been musing on the same question. For my bandsaw a motor of approximately the same speed and power also drives the blade directly. For the sake of a worked example I'll use the dimensions I took from my saw.

Drive wheel is 1 foot in diameter, and runs at 985 RPM. So linear speed of blade is 1 x 3.14 x 985 ft/min = 3000 ft/min in round numbers.

Recommended speed to cut mild steel with high speed steel blade is approx. 100 ft/min. That's a speed turn down well beyond the range of any variable frequency drive three phase or otherwise. Not to mention the problems of keeping the motor cool.

I pretty sure (though I don't know how to quantify it) that the torque requirement to cut steel will go up from that needed to cut wood. So we're into some pretty significant gearing here. I've been musing on whether to make a planetary gear reduction along the lines of the Dore Westbury mill, but it's a lot of work and it's never going to happen.

Having said that, Stefan Gotteswinter says he cuts steel on an ordinary (vertical) bandsaw, but it's not clear what speed the blade is running at. Have a look at the YouTube video of his basement workshop walk-around.

An HSS blade is going to cost £20 or thereabouts a kick, my feeling is that the teeth will come straight off it as soon as you show it a piece of steel. Cutting ally or possibly brass will probably be OK, though the cutting speed is still far too high.

So I decided that a bandsaw designed for cutting wood wasn't a good place to start.

HTH Simon

edit - Jason (as ever) beat me too it.

Edited By Simon Williams 3 on 01/05/2019 19:40:51

Fly press is good at a high force over a short stroke, which is what it is designed for when used for punching or folding. The actual thread converting the handle motion into downwards force is pretty coarse, so it's not the best for use as a pusher in of bearings or a broaching press. You find your self pushing in successive "bumps" so it can be done but it's not ideal. It's big advantage is that the bolster (coming down on the tool) is located well by a dovetail so alignment and pushing square come easily and are built in. But its a big heavy thing that you can hardly put away after each use, so your space constraints may dictate that it's impractical anyway.

A hydraulic press will give you better control over a long stroke, but is much slower to operate. You could motorise it, but I'm assuming this isn't for repetitive use. Various sources of the components exist, the body press kit made by Clarke isn't expensive and gets you started. Enerpac is another option but tends to be pricey. Here's one I made earlier:

This is a very controllable and versatile tool, I use it for pressing bearings, universal joint replacements, also folding sheet metal as you can see. Love it to bits but it's quite difficult making sure you are pushing square. The last broaching job I did with it went through crooked. It's relatively portable so it lives under the bench and comes out when needed.

HTH Simon