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Member postings for John Haine

Here is a list of all the postings John Haine has made in our forums. Click on a thread name to jump to the thread.

Thread: How to machine an ellipse
16/07/2018 23:11:20

This might be of interest


15/07/2018 20:39:27

How important is it that the ellipse is a true shape, is it internal or external, how large, what is the purpose?

Generating an elliptical outline or hole in a plate is trivial using CNC but difficult using other methods.

Thread: Carbide PCB drills and router bit sources
07/07/2018 16:21:34
Loads of suppliers on eBay.
Thread: VFD Choice
03/07/2018 10:20:25

The motor will consume the power it needs to deliver to its mechanical load and dissipate in internal friction and electrical losses. As long as this is less than the rated power of the VFD it will be fine. I think you will find there is a current limit setting somewhere in the inverter setup, you could set this to perhaps 6A rather than 12. If the motor was just running but not connected to a lathe or other machine it would consume much less than its full rated power.

Thread: WM18 CNC Mill Conversion
30/06/2018 09:51:09

I built the electronics for my Novamill, BoB + PSU + 4xDM542 drivers (but I've only ever used 3, haven't used A axis yet) for less than £200 buying individual units from eBay. This didn't include the steppers (already fitted to the machine) but Zapp Automation have NEMA23 steppers at up to ~£30 and NEMA34 at ~£60. You may not need a 34 for the Z drive. Lower prices than these available on the web.

30/06/2018 09:33:36


Thread: Can you recommend a small chuck for centre drills?
29/06/2018 23:19:38


Thread: WM18 CNC Mill Conversion
29/06/2018 23:17:56

Only 2 motors and 2 drivers for a 3 axis machine? Looks a poor deal to me.

Thread: proxxon KT70 CNC ?
27/06/2018 09:24:58

Is this link Of any interest?

26/06/2018 07:06:28

John, all I can suggest is that you do a lot of reading! You might start here and here. First thread has some links to machine suppliers, and also mentions a self-build design that was published in MEW that you might use as a starting point.

Then there are the CNC forums that I mentioned above - they are full of posts on the Chinese routers.

A "pillar" type machine is really a vertical mill. They tend to have limited working envelope unless the machines are very big when they get expensive and heavy. If you want to machine tough metals like steel they are the way to go. But to get a bigger working envelope with a cheaper/lighter machine the gantry router works better but is much less rigid.

Loads of people build them and there are lots of components and materials available to make it easier such as linear bearings, rails, leadscrews, steppers and so on. A good supplier is Zapp Automation. Google "build your own cnc router".

25/06/2018 08:13:11

Indeed, that would do the job though a bit pricey. Actually it doesn't have the 4th axis stepper motor but just the driver for it.

25/06/2018 06:35:16

Search eBay for cnc router 3040 or 6040 - the number is the bed dimensions in cm (30 x 40...)

Huge number come up at wide range of prices. Many come with the electronics and a 4th axis. I gather that when they offer Mach3 it is often pirated and you end up having to buy a copy anyway. I think you can get just the mechanics if you want to roll your own electronics. To get more info and views and advice I suggest one of the dedicated CNC sites such as cnczone, mycncuk, or the Mach3 support forums.

24/06/2018 22:37:38

Many people find the Sieg X1L from Arc a good small mill, and many have been converted to CNC. An alternative if milling metal is not important would be one of the many Chinese gantry routers available on eBay at reasonable prices. I have no experience with those but I'm sure lots of people here have. Just search for CNC milling machine on eBay and stand back...

Mach3 has the benefit of being reasonably priced and versatile. If you want it to run properly using the parallel port then an old 32 bit XP machine is best. It can also run on later Windows machines but may need an external motion controller (for example with a laptop). Mach 4 is probably better, but definitely needs an external motion controller.

Then there is Linux CNC. Many people find it very good, but you need to load Linux on your machine and it is reputed to be hard to get going unless you have Linux experience.

There are several other CNC controller software packages around - UCCNC is one, you'll find others discussed here. Again these need an external motion controller as well as a PC.

You can also buy dedicated controllers that replace the PC. If using a mill platform you will presumably need 4 axes - XYZ & A - that may limit the choice of suitable controllers.

If you are going to start converting a machine then be warned that it is quite involved and you'll need access to machine tools to do it - that may make the gantry router approach attractive if it comes with all the mechanics and steppers already assembled. Another benefit is that they usually have high speed spindles, better for working in wood.

24/06/2018 17:02:35

Mach 3 - you can get everything you can want and more here. It's an application that runs on a PC to control a CNC machine tool. In its standard form it outputs pulses via the parallel port that can drive stepper motor drivers directly. It is programmed either by providing it with G-code or using its internal wizards. M3 Turn however assumes that the spindle is turned in the normal way, if you drive the spindle with a stepper it becomes a "rotational axis" which is best handled with M3 Mill.

IIRC = If I Recall Correctly

Thread: Should a standard turning tool be mounted at a slight angle?
24/06/2018 13:49:49

If you are wanting repeatability when changing between tools, better to make sure any such angle is ground into the tool, not imposed by turning the toolpost. I've gone to a lot of trouble to make a very solid toolpost base that is rigidly located on the cross-slide, and the Dickson block is dowelled to it to be precisely square. All my tools are snugged into their holders and tightly clamped, so I can be sure that it goes back into exact position. Makes CNC turning and I suspect using a DRO system much more convenient.

Thread: proxxon KT70 CNC ?
24/06/2018 13:44:21

The Sieg C2 / Chester Conquest style "7x14" mini-lathe is just about large enough for the size you mention. Often available on eBay at prices 300 - 500 squids.

The book on making the Quorn describes setting up the lathe to make a spiral groove in the main column. IIRC a Potts spindle on the carriage driven from overhead with a slot drill; leadscrew driven by a handwheel and geared down to the headstock. Worth a look perhaps to see how the gears were done.

Thread: Electronics assistance - reduction of output DC voltage
24/06/2018 11:27:00

Indeed, Duncan has it right - A toroidal transformer gives you a big hole to wind your secondary through without affecting the mains primary.

Thread: proxxon KT70 CNC ?
24/06/2018 09:58:02

Certainly an interesting challenge to use an Arduino. However, John's requirement is a bit more complex than driving a rotary table, as he has to drive two steppers simultaneously at different speeds which may or may not have a rational relationship. Also to return each axis to a known starting point after each pass. Mach 3 already has this sorted, in fact it can drive 3, maybe even 4, axes in a coordinated way. So it's clearly possible in software but not straightforward. Arduinos are very cheap (in fact Brian, after seeing your post I ordered 3 of those!) but so are old PCs that can run Mach3 happily.

Thread: What's it called?
24/06/2018 07:43:07

123 blocks will give a limited range of heights in combination, basically in increments of 1 inch. Better would be a pair of blocks of different dimensions. But they seem to me to be of limited use, it's much easier to set the height gauge especially in these days when digital ones are relatively cheap. I've never come across any but the the standard 123 type or a variation designed by the late Sir John which Arc sold (but seem to have discontinued). I have a pair of those and 123 blocks and they are almost never used!

Thread: proxxon KT70 CNC ?
24/06/2018 07:10:16

I bought one of those Proxxon tables to go with a small drill press, also a Proxxon, and it was money wasted. The quality of the table and screws is poor and it's very small. You would be surprised how much space is taken up by your headstock and tailstock and how little is left for for the work.

If you want to the CNC route I suggest either converting a small lathe by adding stepper drive to the headstock, cross-slide and leadscrew; or a small mill such as the X1 from Arc, or a Chinese gantry router - though Richard found its accuracy poor for threading it might be perfectly satisfactory for your purposes..

And depending on whether you want to get lost in Arduino programming as well as all the mechanics, use an established CNC controller such as Mach 3. Actually what you want to do is best done with a mill controller such as Mach 3 Mill as it can drive 4 axes - 3 linear and one rotational.

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