Member postings for Alex du Pre

Thank you for the link Martin, much appreciated. I’ll check it out.

Huub, thank you so much for checking and confirming my suspicions that the 20 degree table on page 114 of Ivan’s book appears incorrect. Interesting that the 30 deg table is correct, I wonder how the error crept in.

I made some 0.75 MOD gears about 15 years ago, using button tools that I assume were based on the 20 degree table (can’t quite remember). They did seem to work ok but maybe because I machined a bit of extra clearance for good luck. I made a Eureka tool at the time which worked ok but was slightly out of tolerance; I am going to remake its main spindle part.

I am looking to make some 0.6 MOD button cutters. The button sizes are really tiny for the gears with few teeth, so I may end up making the gears with 25 or more teeth and buying the smaller ones.

Thank you again.

Huub, thanks from me also for the video and spreadsheet.

I have a question - are the button tool calc tables on p114 of Ivan Law's book correct (Gears and Gear Cutting book)? Ivan's tables do not agree with the results of Huub's spreadsheet or my own calculations from playing with CAD. My calcs agree with Huub's! Ivan's tables give button diameters/separations about 50% bigger. Ivan's tables also don't appear to match the results I would expect using his figure on p113.

To get from Ivan's figures to the values you want, you have to divide his figs by the diametral pitch of the gear required. If using Module gears rather than DP, 25.4/MOD = the DP value. e.g. 0.75 MOD = 33.87 DP.

I'd be very grateful if anyone can confirm, or otherwise, the accuracy of Ivan's tables!

Thank you!

Neil, I have read up on split infinitives once or twice and come to the conclusion that the so-called rule is an affectation with no grammatical basis. I do try to avoid splitting the infinitive, however, unless the meaning or readability requires otherwise, in which case I split without guilt!

I'm trying to get to grips with the Arduino. Hoping to use it as a basis for some control functions for my MkII Fifth scale model car:

http://www.amdengineer.com/mk-2-15-scale-rc-car/

possibly for an automatic gearbox, to control the lights, or even as an ECU for the engine! Endless possibilities!

Regards,

Alex

All, many thanks for the interesting and helpful comments and links. Certainly no excuses not to get started now! I recently found a book entitled 'Lost-Wax Casting' by Wilburt Feinburg in the library, which is worth getting hold of. It's aimed at casting in third world countries so focuses on doing things with locally-sourced materials (mainly clay and animal manure!) but some good ideas for those of us who like to do things with minimal expense. In fact I subsequently found a PDF of this book on the internet, but I am reluctant to give the link as it is probably not a legitimate copy.

Best regards,

Alex.

Hi all,

The novelty of machining parts from billet is starting to wear off and I am looking to add home casting of aluminium to my repertoire of techniques, particularly lost wax casting. There does not seem to a lot on this topic in the forum so I was wondering if anyone has any experiences or advice that they would be willing to share. I'm thinking of going down the home-made gas fired furnace route.

Alex

All - just following up on the above for those who are interested! I spent the evening examining the spindle thread following the suggestions above. I couldn't see anything wrong, but gave the thread plus those in the chucks a good brass-wire brushing - no improvement. I finally decided to fit a threading tool to the tool post and run this up against the spindle thread with the appropriate gearbox setting (rotating spindle by hand). This approach highlighted a significant bruise on the thread, which I 'screwcut' away. The result of this was that the jamming chucks and face plate now screwed on freely, hence this must have been the problem. How it happened, I dread to think! Tests with the DTI showed a much improved, but not perfect, run out.

I'm not sure I would have found this without your help, so thank you!

Alex.

Gents, many thanks for the suggestions. I will have a closer look at the threads for embedded swarf and other bruising/damage. I will report back!

Hi folks, I noticed my Super 7 chucks were visibly not seating properly against the shoulder on the spindle nose. Fearing a bent spindle, I clocked the shoulder and the parallel portion of the spindle but there was no measurable run out. Clocking a lathe test bar also showed nothing amiss with the spindle taper. I clocked the face of my 3 and 4 jaws and the faceplate and this showed a consistent run out at the same position relative to the spindle (the outside edge of the faceplate gave a TIR of 0.2mm). My threaded ER32 chuck gave the same results.

I have scraped and the male and female threads and can't find any muck in there, but the 4 jaw and face plate are very tight screwing onto the spindle; the ER32 chuck is free.

I suspect something wrong with the spindle thread, but can see nothing obvious. Do I dare run a die or threading tool along it? I could also pass a tap through the chuck threads to clean them up - is this wise?

I would be most grateful for any thoughts on what might be wrong and what I might do about it. I have some work coming up that requires a true running 4 jaw and faceplate. Many thanks for reading this!

Alex.

Many thanks for the suggestions. I am in Bristol and I am certainly not the person who comes up when you do the google images search as suggested above - sorry to disappoint you!

Alex.

Hi all, can anyone recommend a laser cutting company who will cut up to 2mm steel sheet from my CAD drawings?

I couldn't find much on this topic in this forum. I would also be interested in any experiences of laser cutting.

Thanks!

Alex

http://www.amdengineer.com

Edited By Alex du Pré on 30/03/2013 06:33:09

I also have a Warco CY90! It lives under the bench on the floor and is dragged out for use. I am going to make a wheeled trolley for it to make this easier. The bandsaw is a real time and effort saver, I have been very pleased with mine. The cut is reasonably smooth and accurate. It can't operate as a vertical bandsaw, unfortunately, but bear in mind that a convertible machine such as this will be quite limited in vertical mode as the width of the blade will only allow straightish cuts. As mentioned elsewhere in the thread, some home-made accessories to enable workholding of small items would be well worthwhile.

Hi all,

I am designing a model four-stroke engine in single and four-cylinder versions. I am thinking about water cooling arrangements. Is it ok to have cooling water in direct contact with the iron piston liners; should I worry about corrosion and how would I seal the water-jacket/piston liner join?

The design has an allow cylinder block with cast iron liners.

Many thanks!

Alex.

Edited By Alex DU PRE on 14/02/2010 10:13:13

Pretty good value.

I have always received good service from Warco and would recommend them.

The lathe has a good capacity and is capable of turning large work-pieces. The large spindle bore (25mm) is very handy.

The machine comes with a good range of accessories - faceplate, 3-jaw chuck, change wheels, fixed and travelling steady, centres - although a 4-jaw chuck is the first thing you will want.

The machine is built to reasonable accuracy. It is possible to work to a tolerance of +/-0.02mm without too much difficulty.

The gap between the milling head spindle and the cross slide is very large, even with the spindle fully extended. Unless you are using a very tall workpiece, some sort of raising block will be needed, which largely defeats having such a large machine table. This is a very frustrating feature and required extra equipment and much time to set up, and significantly reduces the functionality and usefulness of the milling/drilling fixture.

The machine is very noisy. The pulley bearings are rough and noisy, particularly in the milling head.

The need to change belts to adjust spindle speed is time consuming and frustrating.

Changing the gear-cutting gears is very time-consuming - the gears are very stiff on their shafts and are extremely difficult to remove. Brute force is often required. Because of this, I seldom resort to screw-cutting or using the power carriage feed. It just takes too long to set up.

Between-centres turning is all but impossible. The width of the milling table severely limits the movement of the carriage in the X direction (along the lathe bed). This means that if the cutting tool is set up to cut the left hand end of the work-piece, you cannot reach the right-hand end and vice versa. This is compounded by the fact that the carriage is prevented from traversing fully to the left by a lathe holding-down bolt, and the lack of significant overhang of the tailstock. Because of this, it is not possible to turn a constant-diameter (or tapered) shaft in one pass. This is a huge limitation.

The lack of tailstock overhang is a problem, which is compounded by the width of the milling table. In addition to the between centres problems (above), the tailstock has insufficient reach to allow drilling of a workpiece held in the chuck. This is compounded when the workpiece is short and a small drill or centre drill is used. I have got around this by using a MT3-MT3 extension sleeve but this does not resolve the between-centres problems - it also compounds the inaccuracy of the tailstock alignment and results in reduced rigidity.

There is some play in the carriage movement. I cannot remove this without over-tightening the gib-strips. This means that with the cutting tool mounted on the left of the cross-slide (as it must be) the tool cuts deeper when traversing the carriage from right to left (and vice versa). The effect is reversed for boring operations. This is not a big problem, but is an annoying niggle.

The 4-way tool post is a useful feature. However, it is not good quality, and repeatability of positioning is poor. For reasonably accurate work, it is necessary to re-measure the depth of cut each time the tool post is rotated. This makes production work unnecessarily time consuming.