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Member postings for William Chitham

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

Thread: Diamond wheel dressing - MEW 297
18/09/2020 13:35:29

Bought mine from Machine Mart, no complaints: **LINK**

William.

Thread: Cheap Power Feeds for 626
10/09/2020 14:01:52

I'm about to spend more than I can afford on a 626 milling machine and I want to fit a power feed to the x axis. I'm considering a cheap and cheerful "handbag" style one, lots available at around £140. Any advice, comments etc from anyone who has tried one would be most welcome.

Thanks, William.

Thread: Supporting both ends of stock in lathe
27/08/2020 17:57:42

The question reminded me of this Tom Lipton video: https://youtu.be/thrvEhufJJM

Obviously not directly comparable since he's turning plastic but maybe some of the techniques are relevant.

William.

Thread: Diamond Lap for sharpening Brazed TC tools
06/08/2020 13:55:16

They are all the rage: https://youtu.be/1d3PYMsqjsk

William.

Thread: fitting wedge type qctp to Warco WM240
21/07/2020 11:10:48

Could you make a big washer/spacer to fit round the boss for the toolpost to sit on?

Thread: Science Museum needs help identifying mystery objects
20/07/2020 14:47:36

The brass mallet like thing reminds me of the tools I have seen used for tamping sand into moulds for sand casting.

Thread: Boxford aud
16/07/2020 09:44:45

Mine is pretty noisy too with the feed engaged, I reckon lot of it comes from the idler gear. The bearing is quite worn and it rattles and clanks when engaged. I'm considering how to fix the wear, maybe a bush (oilite?) or even ball or roller bearings. I have made a couple of new gears out of Delrin and it definitely runs quieter with those fitted. Thick grease can help, eg chain oil.

William.

Thread: Boxford model A gears
16/07/2020 09:35:54

There was a thread on this topic recently: **LINK**

William.

Thread: Is Iron / Steel endlessly recyclable ?
15/07/2020 15:24:29
Posted by Roderick Jenkins on 15/07/2020 15:00:48:

Most steel is made by blending a mixture of scrap and iron from a blast furnace. I empty my workshop scrap bin into the metal skip at my local recycling cente.

Rod

Does it matter if you mix up ferrous and aluminium?

Thread: Making a 25 Hole Plate For a Spin Indexer.
15/07/2020 15:19:10

I expect this is old hat but thought it might be of interest to some. I have a spin indexer capable of 1 degree increments but needed to cut a 50 tooth gear ie 7.2 degree increments. With a DRO newly installed on the mini mill I set out to make a new plate to enable 50 divisions. Rather than drill all 50 holes I decided to drill 25 in the plate and a separate set of index holes in the indexer body and whilst I was about it i thought I might as well make it good for 100 divisions as well. the hardest part was actually drilling the holes accurately, took three goes to get it right. The holes in the body came out a bit over sized as well, hence the new pin so a set of reamers are on the wish list. More photos in an album.

spin indexer 25 hole plate 011.jpg

William.

Edited By William Chitham on 15/07/2020 15:20:42

Thread: Tufnol Tumbler Gear
13/07/2020 16:12:22

Of course you did the right thing. Making gears is fun.

Thread: Leadscrew suppliers
08/07/2020 09:59:52
Posted by John Haine on 08/07/2020 09:27:50:

Was the original 1/8" pitch? 3 mm is an awkward number for dials. 2.5 mm would surely be better?

For some reason 2.5mm pitch screws are vanishingly rare which is a shame since that is what I need for a Boxford crosslide.

W.

Thread: Mill unexpectedly cutting crooked
01/07/2020 12:06:24

I'm an absolute beginner but it occurs to me that if the cutter isn't perfectly aligned with the spindle it would describe a cone which would create an undercut, for example if the cutter was bent. If it happens with different cutters then maybe there is some crud in the spindle nose that prevents the collet from seating properly or maybe even the spindle is bent?

William.

Thread: Pulley Sizes For An X2 Clone Conversion
25/06/2020 12:19:47

Thanks Neil, is your conversion single speed? Looks like a 4:1 reduction which equates to the low range on the standard machine as far as I can judge.

William.

Edited By William Chitham on 25/06/2020 12:42:56

25/06/2020 12:00:33

Ok, I'm convinced, poly v it is. Some further questions occur to me:

How many ribs? 4 seems common, but I have seen suggestions that 3 or even 2 would be adequate. Less ribs means less "stack" height which might be a good thing but more important seems to be the built in torque limiting safety factor - fewer ribs presumably slip sooner. The weak intermediate gear that we want rid of seems designed as a sacrificial component, primarily protecting the back gears buried behind the spindle which will be redundant anyway but is it realistic to hope that belt slip might reduce damage to cutters or workpiece perhaps in a misread decimal point sort of scenario? It might be interesting to make 4 rib pulleys and try running 4,3 & 2 rib belts to see whether slip could be provoked.

How necessary is the flange? Seems to me that it is only going to make speed change more awkward. If it is keeping the belt on when running then something must be seriously wrong with alignment.

Is there any reason to try to extend the speed range beyond the standard?

William.

24/06/2020 10:02:30
Posted by Clive Foster on 23/06/2020 23:22:18:

The poly vee belt grooves are sufficiently small that you can just go straight in with a tool of the correct shape. Think thread cutting without the traverse along the bed.

Even without a DRO precise spacing is easy with a simple spacer the same thickness as the inter groove spacing and something to clamp on the bed to define the saddle position........

..............If there is no suitable machined surface on the saddle I'd also fit a suitable flat pad to the saddle to give a really good surface to register from. Choose the dimensions so you can add a micrometer later.

Need to generate the shape of single groove pulleys because the Vee is generally too large to be cut in one go with a simple form tool on home shop type machines. Basically you have to cut the two sides separately and maintain the correct spacing. So you are still stuck with getting the spacing right.

Clive

Thanks Clive, that all makes sense to me, I absolutely take the point about the small form tool. I'm actually in the process of making a bed clamp for a dial gauge which would serve the purpose for spacing.

William.

23/06/2020 09:42:05
Posted by oldvelo on 22/06/2020 22:28:05:

Hi

After buying an X2 Mill drill over 10 years ago with 2 speed plastic gears and spring assist on the cutting head. Rebuilt it with Taper roller bearings spindle. Fabricate and fitted Two Speed poly vee belt drive four ribs "J' section. Sold off the motor and controller and replaced with a 1.25 hp DC motor with a AC to DC variable speed Minarik Regenerative Quadrant 4 Drive Controller. Ditched the spring assist for an air spring mounted inside the column with adjustable yoke assembly to get maximum travel of the spindle. Now it is hard to recognise as an X 2 mill both in looks and performance. It is not pretty but is practical.

z-axis 15.jpg

Crikey, there should be a separate thread for most radical X2. Looks as if you've addressed the terrible fine feed as well, does the spur on top of the spindle pulley drive a powered feed?

22/06/2020 15:20:39
Posted by Oldiron on 22/06/2020 12:17:17:

My motor pulley has OD's of 25 & 35mm and the spindle pulley is 60 & 75mm. The V's are 4mm wide x 3.2mm deep

Thanks, is that on a similar machine? Do you use the low speeds much?

Posted by Keith Long on 22/06/2020 12:38:54:

William, look at the page in your link, there are 3 boxes on the right hand side, "Description", "Technical" and "Reviews". Click on the technical box and it tells you the minimum pulley pcd there. Also you can down load the full Optibelt catalogue from www.optibelt.com

Thanks Keith, staring me in the face of course. Spec looks fine, 20mm on the motor and 80 on the spindle gives me the 4:1 and the 2:1 for the high speed should be easy.

I am keen to make this myself because I'd rather invest time than money and I might learn something along the way.

Clive, I can see that a poly belt might be superior but all the conversions I've seen so far use a basic V. Not sure how machining 5 precisely spaced grooves is easier than one big one, could you expand on that?

William.

22/06/2020 11:39:30

Having broken my second intermediate gear I'm contemplating a belt drive conversion for my X2 clone. This looks to be a suitable belt: belt but I can't find any specs for pulleys, specifically I want to know the smallest practical. If I drive the spindle direct I reckon I need a reduction ratio of roughly 4:1 to match the existing low gear setting. The spindle pulley is limited to around 80mm pcd so the motor pulley would need to be 20mm pcd to achieve that - seems a bit tight but it is a small cogged belt. Any thoughts?

William.

Thread: Single point threading
26/05/2020 13:20:39

Three suggestions from a beginner:

Grind an HSS tool with a narrow nose that you can use in with the centre.

Turn the blank long enough to get the centre in to support it then cut to length after threading.

Also maybe skip the gutter or cut it with a radiussed tool to reduce the stress riser.

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