Member postings for Muzzer

Apologies if you already aware of this but there is a large library of free CAD models available here **LINK**

In particular, the section "Mechanical systems and components of general use" has fasteners, bearings, gears, shafts etc. You can choose to download the 3D model in just about any of the main CAD system formats.

Although the commercial motive for this concept is to lead to orders for the components, the CAD models may be a useful starting point for creating your own components. You can register and download all models for free and edit them without restriction as far as I am aware. They are mostly metric of course but this may only be a problem if you are working on an existing application that is imperial and for some reason the component can't be scaled.

Merry

Edited By Muzzer on 02/02/2014 02:05:29

Here's another recent thread you might find useful:

**LINK**

Murray

Yes, it seems clear that the Harrison gears are a larger diameter and the ones that John S has are also larger if they are indeed Colchester. As I noted above, mine are 22mm OD ie presumably 7/8" shallow.

John - sounds as if you have the BS 46 1929 spec which may be similar if it mentions a "6 spline shallow". If so, could you send me a photo of the critical dimensions? Short of coughing up 200-300 quid for the full BS 2059:1953 spec it doesn't look as if I will easily get my hands on a copy. With only a 0.8mm step, it's hard to tell if the faces are radial or angled and also if the faces are all at 30 degree increments.

Thx!

I'm probably looking for BS 2059:1953 Part 1 "Straight Sided Splines and Serrations". These are non-involute splines, it seems.

Machinery's Handbook which is US-focused makes a passing reference to this: "Part 1 of the standard deals with 6 splines only, irrespective of the shaft diameter, with two depths termed shallow and deep. The splines are bottom fitting with top clearance". I guess mine will be "shallow".

I have the 1600 model which is pretty much the same as the 800. It's got an Imperial leadscrew and gearbox but all the slides and tailstock are metric which seems to be not uncommon. Most of the threads on the machine are imperial and the machine was made in the late 60s.

Apparently the change gears are 16DP and they have a 6 splined bore with straight sides (the splines that is). It seems unlikely they are metric, as the metric std for splines of this size would have a depth of about 1.5mm (and a pressure angle of 30 degrees). My digital calipers measure the 2 diameters as 20.6mm and 22.2mm, so much shallower at 0.8mm. That would be 7/8" OD and possibly 13/16" ID.

It's possible that Colchester just made them up but there may have been a prevailing std at the time. I'm probably going to end up milling these splines on the rotary table with a std end mill but I'd like to get the angles and measurements fairly close.

Edited By Muzzer on 30/01/2014 04:49:51

I'm hoping to machine a splined shaft to take the change gears on my Colchester Bantam. Although I have a set I can make measurements from, ideally I'd have an original dimensioned drawing to work from.

Does anyone either have a dimensioned drawing showing the splines or know if they are based on a British Standard perhaps?

Thanks

From what has been described above, it sounds as if cork would be very difficult for most of us to machine using single point tools or blades.

I've recently been "machining" some vulcanised natural rubber strips. These are actually snooker table cushions and are very elastic (they need to have a very high coefficient of restitution) and pretty soft. I had to taper them at each end where they merge into the centre and corner pocket areas.

My first thoughts were to try some form of sharp blade (ouch!) but this was clearly not going to work. Even with a very sharp wood chisel and a smart blow, it's impossible to place the cuts anywhere near you need them and blend the surface acceptably. I also tried some very sharp tin snips and the result was pretty awful.

The solution in the end was to hack off the bulk of the material with scissors or snips and then use a belt sander to remove the rest. As you can see from the test piece, you can get a very reasonable result indeed. Believe me, this is a miraculous improvement compared to the first attempts with the cutting tools. Just keep yourself to one side unless you want rubber crumbs everywhere! Of course, this is what the professional snooker table restorers do.

I imagine something similar would work very nicely for cork. If I was planning to "turn" cork, I would probably mount a Dremel tool in the tool post and use a fairly coarse one of those sanding wheels.

Muzzer

I've put it on my Google Drive here **LINK**

Once you've clicked on the link, you will see a download button at the top left next to the printer icon. It'll be easier to browse a local copy after downloading it from Google Drive (unless you are too paranoid to do so).

It's 13MB, whether it's zipped or not. Quite a bit of interesting stuff in Part II (page 145 onwards). This guy knows how to Google!

Edited By Muzzer on 15/01/2014 04:14:09

Yes, it's a Burnerd Multisize chuck. Very nice and accurate (and solid). Recommended if you can find one with D1-3 mount in MEW ads (keep your eyes open). This is the key operated version. I also have the lever operated version but it's only sensible for repetition work which I never do - too much of a gadfly.

Muzzer

BTW, if you have an hour or two spare, here's an interesting free book(?) in PDF that has a whole load of stuff about 3D printers and where things are going. Mostly for the amateur but some interesting information also about CNC micromills, laser cutters etc. **LINK**

Dunno what the guy does but he seems to have spent a few hours typing stuff out! Pretty comprehensive state of the nation information though, nicely researched.

As these printers are essentially lightweight 3-axis CNC machines running g-code and come with the necessary controllers and compilers, there is a lot of interesting development going on here. This can only speed up the development of CNC technology and its availability to the likes of us - and the broader masses in general. Bring it on.

Muzzer

PS - Since this morning, the PDF has been removed for moderation. Hope it returns soon, otherwise I can post a link to a copy on my Google Drive or Skydrive.

Edited By Muzzer on 14/01/2014 20:14:25

The main issue with adaptor plates is that I have a selection of chucks and faceplates and don't want to disassemble them each time just to use them - and I don't want to go out and buy a load more chucks with a different mount. My adaptor height is set by the length of the Camlock pins. The collet chuck exaggerates the height stackup but there again I have a full-sized machine so it isn't usually going to be a problem. What milling machine do you have?

I'll send you the files when I get home. When you are ready, you can install Geomagic and have a go with the trial. The basic version is pretty cheap to buy if you find you like it. It wasn't too bad really.

Muzzer

I created these parts in Alibre (now called Geomagic) using the 30 day trial. I also saved them as .PAR and .ASM files which work with Solidworks and Solid Edge - and 3D PDF files (for the models) and PDF (for the drawings). However, you lose the history (feature) tree when you export to another application like this, so if you wanted to edit them yourself it would be preferable to use Alibre. So if you have any of these CAD applications or just want the PDF and dimensioned drawings, that's no problem - let me know. Apart from the mounting bolt holes (to suit your setup), you could make most of it from the drawings.

If you are planning on using one of these with a rotary table, it would be convenient if yours had 3 slots to start with. The D1-3 and D1-4 noses have 3 studs and my challenge was getting the 3 studs to co-exist with the 2 mounting slots within the adaptor. As I said, my task would have been easier if I'd started with a larger diameter lump of steel but I was brassic at the time, having just coughed up for a.....rotary table.

A lot of the work is done on the rotary table, so if you have one of these already, creating the fixing holes early on helps the workflow. I also found the DRO I fitted to my milling machine to be invaluable and I suspect I'd have made a pig's ear of it otherwise. I used a centre finder a lot on this job during setup with the DRO and I'm ashamed to admit I hadn't realised how they are supposed to be used until this point! The power of Youtube!

Apart from the various boring operations, careful setup of the 3 cams in the 4-jaw was the other critical activity but it all worked out nicely in the end. I've now used it a few times since I made it and it's been pretty useful.

I'm really not likely to write up anything for the magazine. I'm much more inclined to use my free time in the workshop but you'll notice I've created a couple of short photo journal type postings like this which I hope people find interesting in the same way I do when I browse other people's work looking for ideas and inspiration.

Muzzer

My company (of which I am the engineering director) designs quite a few diecast and moulded components, connectors and housings. We use these in the manufacture of finished products in volumes of over 150k parts per year so we like to have a good idea that the parts we design are fit for purpose. Currently if we need prototype samples of intended volume components we have to have them machined up from solid (either metal or plastic) - or printed by an external partner. It often takes the best part of a week for the CNC machines to be programmed before they even start to make the parts.We certainly wouldn't find it easy to justify buying our own full blown stereo lithography machine but at this price point it makes sense to go for one of these 3D printers in-house. It's very helpful to see Andrew and JohnS giving them a good workout and sharing their thoughts and findings with the rest of us - for which many thanks.

We could be handling and using a usable connector, cover or winding bobbin within an hour or so of completing the 3D model. Certainly the tolerances and surface finish are perfectly adequate for our purposes. Used appropriately, I see a lot of real benefits for a very reasonable cost. Obviously it may also come in handy for turning out our own parts - we will be happy for our work colleagues to do so (within reason), after all we like to have a bit of fun!!

Muzzer

That all sounds rather mysterious but apart from the fact that the cutting edge usually is very slightly bevelled to improve life and make it less liable to breakage, the cutting process within the workpiece is pretty much the same, with a same shear zone and chip formation etc. The additional power required by having this slightly blunter tip isn't a great deal in our applications. I've seen some suggestions that it actually reduces the tool forces.

My Bantam only has a 1.1kW (1.5HP) motor and much of my machining is done some way below this - I can see that from the motor current displayed on the VFD. As for finish, take a look at the results I achieved in this photo I took recently (from one of my albums). This is carbon steel C1025 (similar to silver steel) and the final cut wasn't heavy compared to what I was using during roughing cuts - but not so light that it messed up the finish. I'm pretty happy with it and didn't need to go near it with emery paper - that's how it comes out.

As I said, there are different inserts for light alloys. Apart from the silver coloured non-stick coating, the cutting angles are better suited and an excellent finish can be achieved without requiring a heavy cut.

The main downside of taking shallower and slower cuts (if you have to) is that the swarf doesn't always break up and you can get long spirals of hot, blue swarf flying off. You can always interrupt the feed to break them - or stand safely back!

Get some decent inserts (Sandvik, Korloy, Iscar etc) and give it a go, find out where they are useful. I doubt you'll be disappointed. It's good fun!

Muzzer

It's tilted like that to get all 6 corners usable. The top rake is built into the insert. Some inserts have only a one-sided insert with 3 usable corners and the insert sit flat.

I get pretty good results and very pleasing removal rates with my indexable tools (mainly CCMT inserts which are single sided diamond shaped ones). There are different inserts for aluminium which are worth getting. If you get the cutting speed and depth of cut high enough the swarf breaks up as it comes off (this is how they are supposed to be operated). You get a better surface finish if you take a decent cut, so very fine finishing cuts are actually counterproductive.

I'm sure you get lots of opinions both ways here but used properly(!) they have distinct benefits even for the home user.

Muzzer

You're plain wrong I'm afraid - I've just ordered one like Andrew's.

I have to say they are pretty impressive straight out of the box. For most plastic mouldings and diecastings you would be lucky to even get close to these dimensional tolerances without an additional machining step - at least in the industries most of us work in. It's early days yet, so repeatability isn't known but knowing how these things work helps to explain the tolerances and suggests they should be reasonably consistent.

Muzzer

Edited By Muzzer on 09/01/2014 05:50:53

Hi Nigel

Thanks for your two pence worth! Yes, I appreciate the spring could allow the tool to come free if it were pulled down with enough force during machining in a way that a threaded drawbar wouldn't. I'm taking the Mach-1 system as guidance here and I'm also aware that if I increase the spring rate too much it may become rather tough to remove, as well as stressing the parts if a mis-insertion occurs. As I said, my tooling is fairly low power and low speed, so I'm not going to emulate the capabilities of top end equipment. Generally, I'm expecting that if the spring fails it's likely to do so during the point of greatest compression ie during tool insertion. I use my machine fairly infrequently compared to a professional tool (it's pretty much out to long grass now), so spring fatigue is unlikely to be a concern and at the modest speeds I use, I'm not expecting vibrations to result in unexpected tool release. Hopefully I won't discover otherwise!!

Muzzer

Slightly different tack here but for a 2-stroke CI engine I reckon you could just about make do with 3 moving parts (crank, con rod and piston), possibly even 2 if you used a combined, one-piece spherical piston / rod. Fixed "carburettor", non adjustable compression ratio. Would be a pig to start and would be practically useless but for a bet it might be the simplest possible engine you could build. I expect someone's already thought of that though....

It'll be a cold day in hell when that happens I suspect. For me, machine tools and all the other workshop equipment have always been a means for building, mending and modifying real life things like full sized engines. I just don't have the patience (or interest) to make scale models and if I did, they wouldn't be a pretty sight - I'm more Mad Max than Faberge! "Model engineering" actually means "amateur machine shop" to me.

Merry

John - how do you make these and what material? Dunno if you really made all of them from scratch in one day(?) but even if you didn't, the right method would make a big difference to the time - and time is money.

I'd guess you got the plate cut (laser or water), then some form of CNC machining for the features, with or without some form of turning operation in between, depending on what facilities you have? Not something you want to be doing manually I could imagine.

I'd love to know how you do this. Excellent finish, BTW!

Murray