Member postings for John Hinkley

That worked, Jason. Here's the result, at 50% translucency:

I'll stop posting for the moment. I feel I've monopolised this thread for long enough!

John

And just to keep you up to date, the bronze bar has been ordered and will be in my eager hands before too long, I hope.

John

Jason,

I did try to get a picture to give the effect you are suggesting, utilising the "shaded and all edges " view facility, but the internals are so complicated, it looks a real mess. Having thought about it while typing this, I'll try a "normal" view of the guts and a transparent view of the casing and attempt to combine the two. If it works, I'll post it here.

John

I have taken on board all the leads and suggestions and have decided on the M-Machine metals route, using ½" x 2" bronze bar. By also reducing the angular bearing arc to 120°, I can further reduce the waste material. I don't want to go any less, for aesthetic reasons. It just doesn't "look right".

Thanks, once again, for everybody's input. I think we can consider the matter closed.

John

Ian P/Paul,

Yes, I'm sure that I can optimise the layout to use less material; the drawing was just one I bashed out to illustrate the basic shapes and scale. You're right about the angular dimensions, too. I'll bear that in mind.

I have some aluminium plate 12mm and 10mm thick, so I'm now considering making them out of these in the first instance. Firstly, it will let me practice the machining sequences and by making them 2% oversize, I could use them as moulds later. More thought required. In the meantime, I've got more than enough gear and spline cutting to keep me occupied!

John

Well, I couldn't resist the temptation. Following my post above, I've set to and cobbled together a casing for the gearbox. It involved a few changes to the internals, mind you, to prevent some of the insides ending up outside, or part way through the walls. Here's what I've done so far:

I think I'll need a 3D printer for that!

John

Many thanks to you all for the input. I'll follow them in turn. I particularly like Jason's idea of utilising tubing. That'll be the most materially economic way to do it, I think. I'd only need to get a gas torch and learn to silver solder then!

I'll let you know how I get on.

John

I've suffered a small setback in my effeorts to build my gearbox design. The gear selector forks are supposed to be made from bronze. I asked for a quote for their production and supplied a suitable drawing of the largest of the three. Unfortunately the casting producer has to sub-out the 3D printing of the moulds. The castings would have cost about £65, which I thought was very reasonable, but the mould printing was going to add another £135 or so to the cost! I can't justify that outlay, so I'm thinking that I might have to carve them out of bronze or brass plate. The finished articles are 10mm thick, so we're talking seriously thick plates here. Or I might get away with two brass plates of 5mm, soldered together. I can't go any thinner, or the joint lines will interfere with the machining. Any ideas, anyone? Or alternative suggestions. I could easily fit them on a plate 170mm x 60mm, as below:

John

P.S. The design has changed, slightly since I drew this, but you get the idea.

Mark Gould 1,

To be fair, I have leaned very heavily on the expertise of Mr. Hewland; the design being based on the 5-speed version of the FT200 gearbox that they produce. I have chosen my own gear ratios to suit the scale of the model and it is intended to be a demonstration of the principles of gearbox operation, not necessarily to be fitted to an engine. At least, not in the immediate future - but never say never. I'll take a number of photos of the progress if I consider them to be significant to the build and put them with the others in the album, along with the brief notes which accompany them. From time to time I may well stick a couple in this thread, too.

If I can get into 3D printing, I will try to design a casing to hang it all in, but for the moment my ambition is to support the gubbins on perspex or similar plates so that the workings can be observed. We'll see - literally!

For some idea of size, the input and output shafts are 190mm long and the gears are 1.5MOD, the largest being a shade over 60mm in diameter.

Thanks for your interest.

John

Chris,

With the best will in the world, I think that you'd be asking a great deal to produce a tool such as you have intimated in your drawing with the Grizzly - or any other such T&C grinder. I drew the proposed tool (to scale) and to my mind that is a minute size to aim for. You'll need a microscope as well! Look at this:

That's seriously small and I doubt it would last very long. What exactly are you trying to acheive? There's got to be an alternative way to get the desired effect.

I assume that, quoting Grizzly machines, you are located in North America. Those machines are available in various colours and flavours from a number of retailers at varying prices. All seem to do a pretty good job for what they intended to do. See Stefan Gotteswinter's sie and YouTube channel, for example.

I have no experience of them and not much experience of tool grinding in general, but someone who knows will doubtless be along soon to say I'm wrong and tell you how to do it!

John

Not really workshop progress, but progress nevertheless, albeit with the continuing saga of my gearbox design. I had all but completed the internals, when I found that I'd messed up the gearchange mechanism, such that I'd ended up with the 4th and 5th gear gate in the middle! After a bit of head-scratching (and not a little profanity), I got it sorted with a bit of a re-design of the two offending selector forks and their associated rods. The "finished" design is illustrated below :

Anticipating starting to cut metal soon, I've emailed Abbey Castings to ascertain whether they can cast the selector forks in bronze for me, in a "raw" state, ready for me to machine to finished size, but have yet to receive a reply. Perhaps they are on holiday? I'll try ringing on Monday.

John

I seem to remember that my Frogeye Sprite had a similar strut arrangement to support the open bonnet. Replacements are available, but at a price ( around forty quid !). Could you not use a gas strut such as are used for tailgate lifts? Plenty on eBay in various sizes and specs for under a tenner.

John

John MC,

The gearbox started life as a bit of fun with Alibre Atom, to keep the old grey cells active. However, if or when I get around to making it, it'll just be a decorative or demonstration piece, probably using perspex panels to form the bearing supports in order to show its workings.

I'll be posting more pictures in the album as work progresses, should you wish to follow it. Don't expect rapid progress, though!

John

As you've had no response, I'll tell you what I think.

My VMC mill is slightly older than yours, so I'm unable to answer your question directly. However, if Warco say that the X-axis drive fits straight on, I'd tend to believe them. Mine is an Align unit and it, too, came with a casting for fitment to a Bridgeport. It wasn't used, of course, but the power feed was relatively easy to fit, so long as you observe the end-float requirements and use the enclosed shims accordingly. I'm really glad I got the power feed with my mill - it makes a big difference to the finish, I've found, particularly on long traverses.

HTH

John

I think you're dreaming! Milling parallel to 1/10,000 of an inch!! I'd be happy to get within 10 thou with my machine ( a Warco VMC ). Surface grinding might come close to your requirements, even then you are talking about accuracy not normally attainable with "hobby" kit, even if it's at the top end of the market.

I'm by no means an expert and someone who is will soon shoot me down in flames if what I said is balderdash!

John

Meantime back at the ranch ............

I've done a bit more with the gearbox internals:

The reverse gear idler is missing from this shot. I need to find out how to insert a new offset axis in Alibre Atom. And the shaft ends aren't complete, yet, either. But it's progress.

John

Today I finished the construction of the cylindrical grinding attachment to Stefan Gotteswinter's design and I am very pleased with it . I've still got to get a mains plug for the power supply unit, but I've no reason to think it won't function as intended. ( Famous last words ........ ) Here's what it looks like:

I have made exhaustive use of the surface grinder to true faces parallel where required.

John

P.S. Blast! Just noticed that I've forgotten to drill and tap the hole for the drive dog. Lucky I didn't lock the workshop up when dodging the thunderstorms as I came in for lunch!

Vic,

As it happens, I needed to bore a recess for a bearing today and so I used the Sandvik boring tool that I referred to above. The recess started as a through hole of 6mm diameter, but could have been smaller, if necessary. Here it's in use in the lathe, but would have been equally at home in the boring head in the mill as well.

John

Vic,

To briefly return to your original request - I have had one of the 50mm size boring heads and it has served me well for several years. There are numerous suppliers on the web for these devices and I suspect most are very similar in quality and construction. I can recommend one of this type.

The minimum diameter of bore that you quote from the Arc web site is probably the minimum acheivable with the supplied brazed carbide insert tooling. I have not found these to be very satisfactory, but that's more than likely due to my inexperience. I purchased a Sandvik boring tool off eBay for less than £10 delivered, from a UK source and it is excellent. It has kept its edge and is also used in a dedicated holder in the lathe. It will bore down to 10mm diameter. If your pockets are deep enough, I understand boring tools are available for diameters as small as 0.3mm. That should be small enough for you!

John

Vic,

It's not the size of the boring head that determines the size of the holes that you can produce, within reason, it's the boring tool itself. If I were you, I'd go for a 50mm boring head, to part future-proof your investment and get a suitable, good quality, boring tool that will cope with small diameters.

John