Stirling Engine : Laura

Those interested in technique might enjoy this

MichaelG.

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

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

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.

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

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

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

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

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

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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

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

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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.

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........

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)

Brian, I was in Allied Bearings this morning picking up some parts and took a look at the Kinchrome drill presses there. They did not have the small one in stock. A mid-sized one ($500!) had about 1mm of play in the quill at full extension. So it looks as if they have gone much the same as all the others.

If you are still having trouble with the parting tool chattering and cutting crooked, it could be a matter of the cross slide not set up right/loose.too,.

Edited By Hopper on 21/10/2015 05:40:53

Hopper : yes, they all look to be the same. I guess I will have to live with it and work around it ie. stick to working at the top of the throw.

Parting off problem solved : when I was getting a dome shape on the 19mm discs somebody asked if there was an angle on the parting off tool. There was an angle so I had filed it off flat. But it would appear that an edge is needed so I used the bench grinder (first use of this tool ! ) to restore an angle. The original angle had the leading edge on the left but I put the leading edge on the right to eliminate the dome effect on the disc. This seemed to work well and the brass peeled off nicely. I managed to successfully part off three 25mm discs today. I put the discs in the chuck supported by washers to take a facing cut and clean it up, taking it back to the required 4mm thickness...well close to it !

I will make a few more 19mm and 25mm discs tomorrow. I am not confident of cutting out the cranks and I think I will be going through a few before I get it right. I need to plan this operation better as I cannot do it by eye.

 I was not initially parting off with the work piece supported at the back by washers as per the photo but after cutting two discs there was not enough brass left so  I decided to see if I could cut a third by using the washers...getting a bit cocky now !

I did not have any luck supporting with the tailstock as it left a chamfer on the inside of the hole even though I had only screwed it in lightly (or thought I did). Once I put an edge on the parting tool then there was no need for it anyway.

Edited By Brian John on 21/10/2015 08:35:44

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NOTE : I did try using the tool upside down and running the lathe in reverse but the blade of the tool kept getting pushed in ! No matter what I did or how tightly I clamped down on the blade it would not hold so I gave up on this method. Good thing anyway because it made me look for a correct solution to the problem. I am still not sure why the blade would not hold when the tool was upside down ?

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Brian,

Apologies if I am missing a trick, but I have to ask ... If you just inverted the tool: Where did that put the cutting edge in relation to centre height ?

MichaelG.

Far too low... I realise that now. I have just checked and even if I had used plenty of packing to raise the tool to its maximum height on my lathe then it would have still been about 2mm below centre height. It might be worth trying as an experiment tomorrow to see if it actually does cut any better when inverted.