Member postings for AndyP

Thank you for an excellent description of the geometry of the jig Clive, I may have finally got my head round most of it. Just to be clear when talking about "offsetting the trough" do we mean that measurement that would be affected by placing a washer in the adjustment position on the jig - the one calibrated as 49 deg 59 deg etc

As it stands my jig is going to cut a huge amount off the heel of a new, presumably correctly shaped, drill before getting to the cutting edge so I think I need to experiment with greater projections or look at making Gray's eccentric pivot and render the offset adjustable - it is 7mm at present.

Andy

As I read the instructions that lip stop can only be up against the helix of the drill behind the cutting edge so there would only be one position for any given drill size.

May be the order of setting the offset and the lip stop is important - I'll go and play.

Andy

Ok I have played and it would seem that if I set the drill to protrude by half it's diameter from the end of the trough and then position the lip stop the angle looks a lot better (that is, the cutting edge of the drill when viewed end on is closer to vertical), I could get it closer to vertical by eye but believed the amount by which the drill protruded from the jig was important for the geometry of the thing. 

Edited By AndyP on 15/05/2014 21:35:37

Ok so this thread prompted me to go out and buy one of these jigs to modify because I definitely can not hand sharpen drills and I can't afford to get enough practice.

The Draper jig is significantly different from that which has featured so far.

The angle of the pivot seems to be about 6 deg but not a big issue.

The drill holder sits at 34 deg which I think is going to grind a drill with 112 deg point.

This is where the differences get bigger, the offset between the end of the trough and the centre line of the pivot is around 13mm. The photo has the jig mounted with it's pivot in the lathe chuck and measuring to a tailstock centre.

Setting the jig as per the instructions with the drill protruding by half it's diameter as measured from the tip of the lip stop seems to show a slight mis-match in point angle.

This the jig set up allegedly ready to grind, somehow I expected the cutting edge to be vertical, certainly nothing like the angle shown here.

Some of these differences are easy to fix but the offset difference is huge, any thoughts anybody?

Andy

Gary

Using the formula and data here I calculated a safe working pressure of 738 psi for the thin wall 5/32 tube and no doubt the 1/8 would be higher so your choice.

Incidentally if you want dead straight copper pipe in the smaller sizes like this then at the expense of the end couple of inches just clamp one end in the vice and grip t'other end with favourite grips and pull - at some point you will feel a 'give' and there you go - straight tube.

Andy

If you mean the cut out in the rear stretcher for the boiler blowdown valve then mine is U shaped about 7/16 deep and 7/8 wide. It is on the left hand side of the engine looking forwards.

Whilst thinking about stretchers I had to mill pockets in the underside of the large central stretcher to clear the eccentric straps but that might be my slightly agricultural straps.

Andy

Glad you like the C1 so far.

Another vote here for HSS bits, I do have several insert tools to fit the C1 but nearly always end up using HSS, 5/16 is more readily available than 8mm it seems and is about the right size for the original toolholder with minimal packing. I thoroughly recommend the quick change toolpost once packing tools up to height gets boring/frustrating.

Andy

Stevo,

I think you will enjoy the C1, I have had mine for over 7 years (Chester version) and it has done almost everything I have asked of it including all the round bits of a 3 1/2" gauge loco - Rob Roy.

It has its little foibles, like you can't get a centre in the headstock with the faceplate fitted and there isn't a catch plate listed so turning between centres was difficult to work out.

Several places do accessories, Axminster, Arc Euro Trade and possibly Chester where it is a Cobra lathe. I use the quick change toolpost from Arc Euro and am content with it. Some of the bits will make your eyes water though - look up the compound slide for instance.

Andy

Thanks for all the good ideas guys, turned down no problem, tailstock support and motor lightly held in the fixed steady, 200rpm on the Boxford and a sharp hss tool.

I had thought of but discounted an adapter because the damn things are going to stick out an awfully long way anyway but John's advice to "modify the cheapest bit" makes excellent sense - I must try and remember that bit.

Andy

I have resurrected the cnc conversion of my x1 mill and want to turn down the end of some nema 23 stepper motor shafts from 8mm to 6mm and thread it for the handwheel - double ended motors you see.

I had in mind just to chuck the other end of the shaft in the lathe and keep the motor casing still but will this kill the motor?

I've cut the keyways already.

Cheers

Andy

THIS works

I know nought about optics but when I knocked up a version of this following the previous thread the laser spot from my £2 ebay laser pointer was too big so I punched a small disc of thin, probably 0.5mm, copper and drilled a 0.6mm hole in it before gluing it over the diode. Worked a treat in reducing the size and apparent brightness of the spot to a usable level.

Andy

Agreed Robert, a most useful site, I was winding a spring this week for a knurling tool using its instructions. It has been archived by the "Wayback Machine" at **LINK** or maybe more usefully here .

If your local library has a copy of Spon's price book then that is probably the most accurate apart from actual quotes.

Andy

To be fair John Howard used the phrases "in their right mind" and "volume production" so is Myford a relevant example ?

Andy

Neil,

Sorry if I was not clear, it was my intention to say that sand casting was possible using the printed item as a pattern but vacuum investing for "lost plastic" could well be problem. If I ever manage to model something I want to cast then I will report back but don't hold your breath!

Andy

Phil H 1

I got my printer with that exact intention, I cast regularly in precious metals using the lost wax technique so wanted to try a sort of lost plastic method ie burning out the printed master once invested.

I have to say the resolution on my printer is not up to it unless you expect to machine every surface. With that caveat you could use the master as a pattern for sand casting but I have my doubts if my proposed method will ever work because the models are inherently at least partially hollow so the vacuum investing process is going to get plaster in all sorts of places it shouldn't be, It is possible to print a complete solid (well sort of) but that takes a lot longer.

I have a Sumpod which is a reprap style machine using the usual open source software but it is constructed almost completely from 18mm mdf with flat pack furniture style connectors so is remarkably rigid.

My major hurdle has been the 3d Cad part of the process, I have TurboCAD deluxe 2d/3d but haven't got on with it at all.

Andy

The printer in Currys is the Cube from Cubify in the states which sells there for USD 1532, about a grand at current exchange rates so the "retails at £1950" is the usual rip off exchange rate or just marketing bu****it.

Both that one and the Maplin offering are standard filament melters which can be put together from kits by many suppliers starting at around £300, mine completed this year was £280 complete.

Most of the work on 3D printers seems to be done by enthusiasts or small start-ups so innovation and rapid development ought to follow. There is definitely room for improvement in the engineering in many of the designs.

After playing for a few months now my feeling is that this level of machine can not offer the resolution needed for our uses - I wanted to print masters which I would "lost plastic" cast but the finishing required renders it uneconomic.

I have still to source software which will let me mill on the unit using a dremel like head and machinable wax which might be better - the print head seems to be the "weak link" in the concept at present.

Andy

Edited By AndyP on 02/10/2013 16:16:27

Brian,

Original plan on web is here , neat little bender!

Andy

I suspect the thread was pulled because the poster was the seller of the kit concerned and neglected to mention it, this is after all a commercial site and adverts here cost money.

Googling on microwave metal casting will find all the details.

I know moderation is seldom explained anywhere but a placeholder stating the reason for withdrawal would be less puzzling for all.

Andy

Ok too slow - story of my life !

Edited By AndyP on 26/03/2013 20:27:37

Something like this ?