Stirling Engine : Laura

[Brian JohnParticipant @brianjohn93961]

I must be missing something here : the other side of the motor plate is bolted to the green housing with two large bolts. The plate cannot move so I do not see how that bolt / spring does anything ? Are the two bolts on this side supposed to be loosened when changing the speeds ? YES THEY ARE !

The label with the gradings on the front has fallen off already ! I am most concerned about the slight 2mm of movement in the chuck at the bottom of the throw. Is this going to cause problems ?

 

Edited By Brian John on 17/10/2015 07:50:21

[Nick HughesParticipant @nickhughes97026]

Reaming, i was taught that as a general rule/good starting point for steel is 3% of the Reamer diameter, for the Stock allowance (e.g. for a 3/8" reamer the hole should be 0.364" [0.375 x 3 / 100 ]). If the hole is only drilled and the 3% calculation results in an odd size then for softer materials use the nearest Smaller drill and for tougher materials, then use the nearest Larger.

As for using drill shanks to check hole sizes, be careful, HSS drill bits are tapered over their length, but Solid Carbide are generally parallel.

Nick.

 

Edited By Nick Hughes on 17/10/2015 10:49:55

[Ian S CParticipant @iansc]

Brian, the motor pivots on the two bolts on the left side, if you loosen the plastic headed bolt on the right, the motor can be swung toward you to loosen the belt for changing speeds, after the pulleys have been selected push the motor away quite firmly and retighten the plastic headed bolt again. My drill vice is one handed down from dad, it's an old Black and Decker one that he used when he had his B&D drill mounted on a drill stand, I'v also got a cheap tilting one that came with my milling machine.

Ian S C

[Gordon WParticipant @gordonw]

Brian- that drill machine looks the same as mine, but different brand. The motor mounting is a hinge, the screw under the belt cover is for adjustment, there may be extra screws in slots as well. They are not robust machines but ok for light stuff, if drilling a hole in steel you may be able to bend the table with heavy pressure. If so put a small block under to take the force. Mine has more sideways play than yours but works ok for drilling. If I need accurate drilled holes I use the lathe.

[Brian JohnParticipant @brianjohn93961]

Thank you Ian and Gordon. It makes sense to me now. I did drill the holes in the edges of my rubbish cranks (the ones I stuffed up) and it worked well. Now I need a good machine vice to go with it.

[Brian JohnParticipant @brianjohn93961]

My first wax chuck made from a 12 X 30mm brass hex head bolt. 12mm was the largest brass bolt anybody had in Cairns. I also want to make more wax chucks from 16mm and 18mm brass bolts but I will have to buy them from Hong Kong. They cost about $7 each.

The wax chuck was polished on a sheet of glass using 1500 and then 2000 grit sandpaper. I have not had a chance to use it yet.

[pgk pgkParticipant @pgkpgk17461]

Does it have to be brass?

[Michael GilliganParticipant @michaelgilligan61133]

Posted by pgk pgk on 19/10/2015 09:19:56:

Does it have to be brass?

.

Not if you are using modern adhesives such as SuperGlue

However: Traditional Watcmaking technique uses Shellac; which is melted with heat, and permits the job to be centered whilst the Shellac is still soft. The thermal characteristics of brass seem better suited to this.

Note also that the Watchmaker's stubs are typically fitted into a collet and trued-up or modified for a particular job [Brass is more easily worked]

MichaelG.

.

Edit: useful illustration, here

P.S. That page also has some helpful comments regarding M14 threaded chucks.

 

Edited By Michael Gilligan on 19/10/2015 09:49:04

[JasonBModerator @jasonb]

Brian, you don't have to use a bolt, just get an offcut of suitable bar and turn down one end to fit the chuck. Come to think of it you don't even need to reduce the dia just face off the bar as is and stick your work to that.

Here is a bit of bar being used, turned the roughly cut plate round on the lathe and then over to the mill to drill, no metal wasted makeing special chucks, just faced off a bit of bar.

 

Edited By JasonB on 19/10/2015 10:30:49

[Brian JohnParticipant @brianjohn93961]

Jason : but doesn't the face have to be highly polished to get a good glue joint ? I was following instructions on one of the above links on wax chucks.The shape of the bolt is also good for polishing by hand on a sheet of glass. I could make this shape out of any brass bar but why waste brass when the bolt is almost the required shape ?

I did not use a steel bolt because I get a much better finish on my small lathe using brass.

Edited By Brian John on 19/10/2015 10:39:52

[JasonBModerator @jasonb]

I can't see any point in facing the bolt head, taking it out of the lathe to rub on a bit of abrasive and then putting it back into the chuck, its unlikely to go back true. I would not pay too much attension to that link you posted earlier, the chap looks to be getting a very poor turned finish on both the wax chuck and the finished work, there really should be no need to take a file to a finish turned face

As you are not using wax then a turned finish should be quite adequate.

There is also no need to make it that shape just face off a short offcut of bar, its not as though you are trying to fit it into a watchmakers lathe collet.

Edited By JasonB on 19/10/2015 12:29:59

[Michael GilliganParticipant @michaelgilligan61133]

Those interested in technique might enjoy this

MichaelG.

[Jeff DaymanParticipant @jeffdayman43397]

If the drill press truly has a full 2 mm side to side free play with the quill extended as you stated I think you will have endless trouble doing accurate drilling with this machine.

If it is 0.2 mm you may be OK. It would be just about ideal to have 0.02 mm side play.

As I stated in my earlier note one key factor of a good drill press is zero or near zero side play with quill extended.

The second factor for a good drill press is a quiet low vibration motor with adequate power relative to the size of the machine. If it doesn't have such a motor it will not be pleasant to use in the long run.

Again for these reasons it is wise to buy a drill press in person, and if you can't inspect it and hear it run, don't buy it. There are good ones and lots of bad ones on the market. The day I bought the large drill press I now have, the firm had three on hand. Two had lots of quill side play, one didn't. Two had quiet motors, the other sounded like it would explode any minute. I switched a good motor on to the low play quill one, in the store, and bought it. Completely satisfied with it, and it was an inexpensive Taiwan made machine. The store staff were not happy about my in-store rebuild, but they did want the sale, so said little. JD

Edited By Jeff Dayman on 19/10/2015 14:16:06

[Brian JohnParticipant @brianjohn93961]

It is difficult in small place like Cairns to find anybody who will let you run their drill presses before buying. The one I have now rumbles and vibrates like an old steam engine. The movement in the chuck is quite excessive at the bottom of the throw. I guess you get what you pay for and this cost only $100. I probably should have gone with the Ozito brand which was only $40 more. All my other power tools are Ozito (3 year warranty) and they are excellent. However the local Bunnings hardware in Cairns does not carry them for some reason ( I think it is a computer glitch) or else I would have bought one.

A closer inspection indicates that it may be exactly the same machine with a different colour scheme ! Ignore the chuck guard.

**LINK**

http://www.supercheapauto.com.au/online-store/products/Rockwell-ShopSeries-Drill-Press-5-Speed-350-Watt.aspx?pid=287223#Recommendations

 

 

 

Edited By Brian John on 19/10/2015 14:57:44

Edited By Brian John on 19/10/2015 15:00:24

[bodgeParticipant @bodge]

Brian

Sorry to hear of your problems with the the new pillar drill. I have had two of this type of drill in different colour schemes from different suppliers .I am of the opinion that they are all as you describe, So how come i was daft enough to buy two ? Well the price was right at the time, though i knew what to expect for the price, not a lot ! I also knew i was going to brake them up for the parts as soon as something better showed up.

The problem is the quill assembly is sloppy in the main housing / casting, I dont think there is a easy way to fix the problem, the first one of these i used it for a while and i found table deflection to be a bigger issue , so i would set the work piece up close to the chuck and support the table with a small sissor type light car jack . sorry not to be of much help really

bodge.

[Brian JohnParticipant @brianjohn93961]

I tried to cut out some 25mm discs for the large crank today. Everything went well until the parting off. I had problems parting off the smaller 19mm cranks but that was only because of the end shape which had a slight dome in it. This was later rectified by taking a facing cut when the disc was mounted in the lathe (I will try a wax chuck next time). The parting off procedure went reasonably well for the smaller discs.

But today I am having problems cutting through the 25mm diameter workpiece. It does not matter how slow I feed it in or what chuck speed I use, the blade type tool keeps digging in. I have read that some people turn the tool upside down and run the lathe in reverse. How does this help…if it helps at all ?

The brass work piece is 33mm long : half in the chuck and the other half protruding.

NOTE : carriage and top slide are locked in place.

Bodge : that is what I intend to do, set the work piece up close to the chuck when drilling. I was thinking of taking it back but they are probably all the same.

Edited By Brian John on 20/10/2015 08:20:57

Edited By Brian John on 20/10/2015 08:30:21

Edited By Brian John on 20/10/2015 08:36:15

[HowiParticipant @howi]

Brian – an inverted cutting tool running in reverse cannot dig in, the deflection is away from the work, also swarf drops away from the cutting edge due to gravity so less chance of swarf jamming cutter.

I have used this method and can testify to it's worth, especially with hss

I also have a carbide tip parting tool (replaceable tip type) which has proved to be the best parting tool ever.

I use this in the conventional way, not inverted. 

Howard

Edited By Howard Winwood on 20/10/2015 09:00:14

Edited By Howard Winwood on 20/10/2015 09:00:48

[HopperParticipant @hopper]

Beside the upside down blade and running in reverse, try drilling a centre hole in the end of the job and keep the tailstock centre in place until you get down to the last little bit before the cut is finished.

I wouldn't worry too much about wobble at the end of the stroke of your drill press. What's important is the wobble in the first inch or so of movement. This is the area you will use for 90 per cent of model work. You can also drill and tap the drill housing for a couple of brass grub screws, or even slit it with a hacksaw and install a pinch bolt, but you already have one machine tool that needs fettling…

If you bought the drill press from supercheap or Bunnings, I think both will let your return it for a refund if it is "not fit for purpose". It might be worth looking at the Kinchrome drill presses at Allied Bearings but I'd expect they're more expensive at $179 at the moment. They all look the same, made from the same castings but machined and assembled by different companies. Kincrome at least has some kind of quality control checks before they put their name on it. Most of their stuff is reasonable quality, not Snap-On or Stahlwille quality but good enough for home use.

Your best shot for making future 'wax chucks" might be some ally bar a bit larger than the diameter of your crank disc, then turn a recess in the face to match the disc diameter and glue the disc in the recess with super glue or Loctite. Or, even more economical on material, and making parting easier for yourself, turn the outside diameter of the brass crank disc to size then drill and ream the hole down the middle. Then part it off. Then take a piece of scrap bar, eg 16mm, and turn a short section down to fit neatly in the reamed hole. Put the disc on the newly turned spigot and superglue/Loctite it in place.

Edited By Hopper on 20/10/2015 10:00:56

[Ian S CParticipant @iansc]

Brian did you try Supercheap Auto, they have one, same price, and specs as the Ozito at Bunnings, it has the Rockwell name.

Ian S C

[Brian JohnParticipant @brianjohn93961]

Ian : I bought my drill press from Supercheap Auto It is the Rockwell brand. I think I will hang onto it now. As Hopper said, most drilling is done at the top of the throw. I have been to Bunnings today and the Ryobi drill press looks much better quality but it does cost $229.

Hopper : I have already drilled my 6mm hole in the centre for the axle in the work piece so I cannot use the tailstock to support it. I thought somebody had instructed me earlier never to part off when turning between centres….was this incorrect ?

Is there a rule of thumb for facing off or parting off eg. length should be no more than twice the diameter…three times ?

NOTE : drilling out with 5.8mm drill and then reaming out to 6mm gives an excellent result. The supplied axle fits perfectly.

Howard : where did you buy your carbide tip parting tool ? There are no 8mm carbide tip tools listed on ebay.au, only 10mm and higher.

Edited By Brian John on 20/10/2015 14:49:06

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Brian John on 20/10/2015 14:14:05:

I thought somebody had instructed me earlier never to part off when turning between centres….was this incorrect ?

.

No … not incorrect, but:

There is a small, but very significant difference between 'turning a deep groove' and 'parting off'

You can safely use tailstock support for the grooving … but remove it for the parting.

MichaelG

[JasonBModerator @jasonb]

Brian. there is no real problem with putting the tailstock centre into a drilled hole for added support it does not have to be just a centre drilled hole

I sometimes make parting cuts with tailstock support but REMOVE the support before the part is completely free, usually finishing with a saw.

Good to hear that using the correct drill before reaming is working for you.

I think on such a small machine it will be hard to fit an indexable parting tool and the wider cut they produce could cause more problems than it will solve.

Try grinding your parting tool to have less or even no toprake for brass, looks like you are using the same toprake you had for alumining.

Edited By JasonB on 20/10/2015 16:41:12

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Michael Gilligan on 20/10/2015 15:08:43:

There is a small, but very significant difference between 'turning a deep groove' and 'parting off'

You can safely use tailstock support for the grooving … but remove it for the parting.

.

Disambiguation:

"You can safely use tailstock support for the grooving … but remove it for the parting"

Is intended to mean: "You can safely use tailstock support whilst what you are doing can be reasonably described as grooving … but, as that [continuing] operation approaches the stage of parting the material, remove tailstock support."

i.e. I was referring to a transition point in the process.

MichaelG.

[BazyleParticipant @bazyle]

The reason a rear upsidedown parting tool works 'better' is that on old lathes there is often nothing to stop the rear of the saddle lifting up, or it is not properly adjusted to prevent it by at least a few thou. Thus as the tool digs in the direction of force is lifting the tool away. So the method does not work so well on many modern or new lathes but people still adhere to the mantra………. When that doesn't work they get seduced by the carbide insert tool cult……..

[HowiParticipant @howi]

Hi Brian – I got the parting tool from SPJ tools( see advert to right ) don't know if they still do it as it does not appear to be listed on their web site. You could try RDG tools also.

I have used a standard parting off tool both normally and inverted, can't say one was any better than the other.

Brass and aluminium no problem, steel altogether more difficult – best advice is keep tool overhang to a minimum, keep the infeed as constant as possible to keep the tool working ( be brave and let it cut).

Carbide insert tool, best I have ever used, just used it to part off nine cuts of 12 mm square stainless steel, yes! Interrupted cuts and all, with no protest from the insert.

I am a convert, but will probably still use HSS for alu and brass.

My five pence worth for what it matters, does seem to be a black art though and does depend an awful lot on lathe power and rigidity. ( do keep the cut as close to the chuck as possible though)

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