What Did You Do Today (2016)

[john carruthersParticipant @johncarruthers46255]

Progress on my mini lathe, something for the steam engines to drive…

[Michael GilliganParticipant @michaelgilligan61133]

What scale is that model pencil, John

MichaelG.

[Neil WyattModerator @neilwyatt]

I like that John

I'm cursing open source software right now: JOOMLA offered an update, rapidly followed by a new version with bug fixes yesterday.

I can't edit my own website now, DOOMLA won't update to the new (still buggy) version… and the fixes on the the support website don't fix…

N.

[Anonymous]

I'll try and answer all the questions, albeit it with some duplication of the excellent information posted by Nigel.

The horizontal mill is indeed an Adcock and Shipley model 2E. It is universal, meaning that the table can swivel for spiral milling, not the common myth that a 'universal' mill is one that can be configured as horizontal or vertical.

The table feed in on X only. The feed motor is on the knee and drives through gears into a gearbox with two selectors for a total of 18 feedrates:

Drive to the table is via two skew gears, able to cope with the table being swivelled. The table does have a backlash adjuster, which basically rotates a second feed nut on the leadscrew. However, it seems a bit loose to me, so I haven't had the nerve to try it. I can't remember if the table feed motor is 1 or 1.5hp.

I'm a bit puzzled by the 2/3 ratio for low and high feedrates. The main drive motor has a low and high range, in the ratio of exactly 2 to 1, as would be expected by doubling the number of poles. The main motor also switches from star to delta in low range so the loss of power is not a great as might be expected from a halving of angular velocity. The feed motor doesn't appear on my schematic, but I assume it is completely separate electrically from the main drive motor. May be it's some sort of odd 4/6 pole motor?

As Nigel has pointed out the Bridgeport can be used to cut helical gears, even though the table does not swivel. Presumably with a right angle attachment and support one could also swivel the ram and cut in 'horizontal' mode. My primary reason for wanting to use the Bridgeport is to cut high helix angle gears. In theory the table on the horizontal mill can be swivelled ±45º, but I'm struggling a bit with clearances and access with it set up for a 30º LH helical gear. I have a vertical head for the horizontal mill but not the universal head mentioned by Nigel. I've never seen one, or ever seen one for sale, so I suspect they're in rocking horse sh*t territory. However, I do have a right angle attachment for the Bridgeport which can be swivelled to achieve much the same, albeit with less rigidity.

Of course the problem with driving the dividing head by the method shown for low leads is that the gear train from the table has to step up to compensate for the worm reduction. This can lead (pun intended) to large loads on the gears. The manual for my dividing head talks about a low lead accessory, which uses the gear train to drive the dividing head spindle directly. It's a pretty simple device, just a plate with slots (like the existing banjo) and an expanding shaft that fits into the DH spindle. I may well end up making one. However, to use it you have to disengage the worm, so you can't index the head. So it would be fine for milling worms or threads, but no use for gears.

The manual also talks about turning the division plate and using that to drive the table instead of vice versa. Of course this means that the gear train then becomes reducing. I had a quick play with this last night. I think I know how it works, but once I've made the mating LH helical gear I'll break down the set up and experiment in more detail.

Darn it, rather than leaving the question of spiral milling on the Bridgeport as a theoretical concept I can see that I'm going to have to try cutting a high helix gear on it, just to satisfy myself that I can do it.

Another mystery solved. On the dividing head, when indexing if the plunger isn't fully retracted it is possible to 'pickup' the fingers, which rather badgers the indexing. The indexing spring is quite strong and I could foresee I am going to struggle with the limited access. I wondered why the manufacturer didn't add an indent so the plunger could be turned without have to pull against the spring. Then I wondered why there was loose collar on the indexer. Turns out it's the locking indent, except that it's missing the small spigot needed to lock the indexer in the out position. I've found a suitable bit of silver steel, so this evenings job will be to fit it.

And as an aside to those who might be thinking bl00dy cheque book engineers and their toys, the total cost of the horizontal mill and dividing head was about £500; less than yer average benchtop mill.

Andrew

[Martin KyteParticipant @martinkyte99762]

Never mind the cheque book stuff if only I had the SPACE !!! I moved to a larger workshop and the extra space instantly filled itself up with woodworking machines.

Go for it Andrew

regards Martin

[John Stevenson 1Participant @johnstevenson1]

Andrew you can’t use the horizontal head on a Bridgy with the ram skewed over.
The reason being that the more you slew the wider your cutter becomes and passing the blank underneath will cut a wider tooth space

[Ian S CParticipant @iansc]

I'm fiddling around, designing an IC motor similar to a Webster, and as I,m getting to the cylinder head stage I decided I needed a spark plug, and the plug needs a threaded hole, so as I was in Christchurch (NZ) I got a 10 mm x 1 mm tap $NZ42. The plug suggested for models is the NGK CM6, if you are in NZ, don't, it will cost between $NZ13 and $NZ 32 depending where you go, the number you want is CMR6A, same except it has a resistor. I'm going to use the coil from the magneto of a Sthil (?spelling) chain saw, it gives a good spark from 1.5 V, and at 50 mm x 20 mm should be easy to hide away.

Ian S C

[Roderick JenkinsParticipant @roderickjenkins93242]

Pleasantly surprised by the quality of the finish from this CCMT tip in the "use the undamaged corner" holder. Random lump of ally to make a pulley, machined dry. Note the reflection of the tool.

Rod

Edited for a better pic.

Edited By Roderick Jenkins on 19/10/2016 18:10:51

[Roderick JenkinsParticipant @roderickjenkins93242]

While I was at it:

When I bored the pulley, the swarf very tidily fed itself down the mandrel bore. Never had that happen before

[Boiler BriParticipant @boilerbri]

Cut and fitted the new covers for my Britannia which worked out nicely. Took four pieces of card to make the template .

[StovepipeParticipant @stovepipe]

Posted by Neil Wyatt on 18/10/2016 21:19:59:

Many years ago there was trend for people who did crafts with kids using toilet roll tubes to 'sterilise' them first by microwaving them

Neil

And there's me thinking you meant the kids !

Dennis

[Michael GilliganParticipant @michaelgilligan61133]

Armchair Engineering at its finest, tonight:

An excellent TV programme [BBC Four] about the building of the Severn Bridge.

'TimeShift' – 'Bridging the Gap'

MichaelG.

[Anonymous]

Posted by John Stevenson on 19/10/2016 12:59:05:
Andrew you can't use the horizontal head on a Bridgy with the ram skewed over.
The reason being that the more you slew the wider your cutter becomes and passing the blank underneath will cut a wider tooth space

I disagree; if, as the blank is traversed, the dividng head also rotates the cutter will follow a helix exactly the same as using a universal horizontal mill. The same is true for the method mentioned by Nigel, if the head is tilted and the cutting takes place on the side the cutter will follow the helix as the dividing head also rotates.

I would agree that if the dividing head does not rotate then you just cut a wider space parallel to the axis of the table movement. But that would be the case on the horizontal mill as well as the Bridgeport.

Andrew

[Anonymous]

Posted by Michael Gilligan on 19/10/2016 21:56:04:

Armchair Engineering at its finest, tonight:

An excellent TV programme [BBC Four] about the building of the Severn Bridge.

'TimeShift' – 'Bridging the Gap'

A good programme, apart from the ponitificating architectural nitwits. I had to change channels though when they were showing people working on the towers and wires with no safety nothing.

Tomorrow evening on Channel5 there's a programme on Britains Greatest Bridges. Based on the one last week it will be very good. It is one of the very few 'techincal' TV programmes where the presenter isn't wetting their knickers all the time about how super wonderful marvellous it all is, and then gets the explanation wrong. In this programme the presenter is fairly sober and lets the engineering speak for itself.

Andrew

[Neil WyattModerator @neilwyatt]

A little side-project*. I made a couple of brass 'feathers' last night, painted them up with a dalo pen and scratched in a pattern. Threw them in eh ferric first thing and later found time to polish them up. Suitably 'impressionistic'

Now I found 3" of 1mm brass for 'stalks' but can I find the b***y blades?

Photosensitive film and three bottles of fresh ferric arrived today so they may have to wait for a bit.

Neil

*Can you guess what it is yet?

[I.M. OUTAHEREParticipant @i-m-outahere]

I spent the afternoon repairing my ultrasonic cleaner , i went to use it last week to remove some flux residue on the pipework for my Stuart score engine and it took heaps to get even a small amount off which considering a toothbrush and some hot water works fine but i wanted to see how an ultrasonic unit would do the job .

My unit has six transducers controlled by three identical boards and after some fiddling around i deduced that four of the trancducers were not working so apart it came , luckily one board was working so i could use it to check all of the transducers and luckily they all worked .

By comparing some multimeter readings with what i got from the board that worked with the dead ones i deduced that the two switching transistors had dead shorted and blown the onboard fuse , i was beginning to worry that the step up transformers may have shorted but luckily the readings from the good board matched those of the dead ones so some transistors were ordered and other than a fried resistor all was looking good .

The first board reapaired was set up for test and immediately blew a fuse – back to the drawing board ! I really should have known better and checked to see if the dead short was gone before plugging it in !

I found that it had also destroyed one of the diodes in the bridge rectifier so all were changed and the unit re tested – fired up and ran perfect !

The other two boards had both the transistors and rectifier changed and passed a twenty minute trial with flying colours ! One thing i noticed is how much more aggressive the the cleaning effect is compared with when it was new so i suspect that one of the boards were stuffed from the get go – thats what you get for buying off that well known auction site and not from a reputable dealer i suppose .

Ian

 

 

 

Edited By XD 351 on 21/10/2016 07:23:57

[MWParticipant @mw27036]

Posted by john carruthers on 19/10/2016 09:09:18:

Progress on my mini lathe, something for the steam engines to drive…

Absolutely wonderful looking little thing, I imagine you must be proud of that. Is it your own casting?

PS. Like the picture of your daxie, i have a miniature one 

Michael W

Edited By Michael Walters on 21/10/2016 08:23:39

[MWParticipant @mw27036]

Posted by Neil Wyatt on 20/10/2016 18:55:16:

*Can you guess what it is yet?

Is it a decoration for the jovilabe? But thats more a main project than an aside i would take it… or a brass plant ?It's a guess anyway

Michael W

Edited By Michael Walters on 21/10/2016 08:25:15

[Neil WyattModerator @neilwyatt]

Snitch

Neil

[Anonymous]

Well late last night actually – I knocked up an internal gear and associated pinion in 3D CAD, the internal gear is 45 teeth, and the pinion 21 teeth:

The pinion was created from a DXF file downloaded from the net. The internal gear is created from scratch. It was simple to use the cartesian parametric equations for an involute in Excel to create the X-Y co-ordinates for the proper involute curve. I then imported these as a comma delimited text file into CAD to generate the correct curve. First time I've tried importing data, it worked a treat.

Some issues arose with the design. First, the base circle, from which the involute is generated, is larger diameter than the internal diameter of the internal gear. So you have to fudge the involute curve the last little bit. Thinking about the geometry this is dependent upon the number of teeth. The task this evening is to derive the number of teeth at which this ceases to be an issue.

The other issue is that the pinion is clearly undercut. Playing with the assembly shows that without this undercut there will be interference. My plan was to make the pinion using the dividing head and an involute cutter. But that means I won't create the undercut and hence the gears will not work.

So my plan is to change the design to use a 20ºPA instead of 14.5º. That should eliminate the need for undercutting. Then I plan to 3D print the gears to check operation before worrying about how to cut the gears in metal. Cutting the internal gear won't change, it's the pinion that is the issue. I can either buy a 20ºPA cutter from the US, make my own involute cutter on the CNC mill, or make the pinion on the CNC mill. Decisions, decisions!

Andrew

[Anonymous]

Well that turned out easier than I expected:

Probably means I've made an error!

Andrew

[john carruthersParticipant @johncarruthers46255]

>>Progress on my mini lathe, something for the steam engines to drive…

Absolutely wonderful looking little thing, I imagine you must be proud of that. Is it your own casting?<<

Not a casting, just various bits from the scrap box welded, riveted and soldered together.
Made the saddle, the rack and apron today, and started on the lead screw.

[Neil WyattModerator @neilwyatt]

Andrew,

Rather than extending the involute I would have rounded the corners of the teeth, to ease engagement if anything is imperfect and avoid the risk of 'shaving' the inner gear.

Neil

[MuzzerParticipant @muzzer]

What I'd really love to see would be 2 mating segments of involute gears in some sort of CAD / animation where you can vary the radii in both polarities (ie concave and convex gears) and see how the tooth profiles change while remaining involute. I hope I'm not appearing to volunteer myself here, as I don't understand enough or have enough bandwidth to do it at the moment. It's interesting to see how the internal teeth shape differs from the external teeth in Andrew's illustration.

[Anonymous]

Posted by Neil Wyatt on 21/10/2016 17:07:51:

Rather than extending the involute I would have rounded the corners of the teeth, to ease engagement if anything is imperfect and avoid the risk of 'shaving' the inner gear

Even with the involute arbitrarilyextended the gears seem to mesh perfectly well. I was just surprised that the base circle was bigger than the internal diameter, I had assumed that it would always be smaller. I think the same will be true for ordinary spur gears, the base circle can be larger than the root diameter. I might just 3D print the gears as is before modifying them for a different pressure angle.

There are a number of potential interference problems with internal gears, some of which apply only to internal gears. Being a bear of little brain I need to understand the basic tooth forms and how they are calculated before delving into the modifications of the tooth form and when they are required. In comparison the actual machining of the gears should be pretty simple.

Andrew

[Author]

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