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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: Airline Fittings?
02/01/2020 12:42:05

I have split the output from my compressor into clean and oily lines. The clean line has a filter and dryer and everything that plugs into this uses Euro type fittings. The oily line has a filter and lubricator and uses PCL fittings.

Thread: Help with a boxford c
08/10/2019 11:44:59
Posted by Nicholas Farr on 07/10/2019 23:03:31:

there is no tensioning adjustment for this belt on the underdrive models

On my CUD the holes in the brackets for the intermediate shaft are slotted so I was able to adjust the tension somewhat by moving the shaft backwards and forwards.


Thread: Engraving
20/09/2019 15:36:28

I just refurbed a micrometer and used an Edding 950 paintmarker following a You Tube recommendation. I bought it from Zoro, they also do a Markal brand equivalent. They are meant for marking up fabrications, metal stock etc and will supposedly write on dirty rusty oily surfaces and be permanent. Easy enough to apply by the rub on wipe off method, only just done it so can't vouch for permanence.

Thread: Calculating DRO For Mill Z Axis
09/09/2019 17:42:03
Posted by Steve F on 09/09/2019 17:36:46:

I think Machine DRO do a gadget that sums the 2 values together. Yes its here **LINK**

Just the job, I thought it must be possible.

09/09/2019 17:39:36
Posted by HOWARDT on 09/09/2019 17:32:27:

What if you connect the scale to the knee and the reader to the quill. Then you read the distance between the two.

That would work but might require a rather convoluted mechanical connection between the two.

09/09/2019 17:28:47

While my printer toils away I've been pondering the DRO installation on my fantasy mill. Obviously it is a knee mill with a quill and I'm wondering if a 3 axis DRO can be set up so that the Z axis displays the product of two scales, one on the quill and one on the knee? In other words any movement down on the quill would be added to any movement up on the table to show the cumulative result.

Thread: Mains power supply for 12v dc motor
31/08/2019 14:49:17
Posted by Les Jones 1 on 31/08/2019 14:40:16:

Hi William,
I don't think that is really suitable for your purpose. It will be designed to control the speed of a motor designed for around 180 to 220 volts. It will provide no isolation from the mains. It will probably use phase control so when it is set to a low speed (Low AVERAGE voltage.) the output will be short pulses of a much higher peak value than the average output voltage. I am assuming that your saw is designed for an 18 volts battery.


Ho hum, should have asked here first, still, I think there is room for it in the "bound to come in useful eventually " box.


31/08/2019 14:13:04

I just ordered one of these: Link from Bangood. Hoping it will run a small circular saw with a dead rechargeable battery. Spec claims it will produce DC 10-220V, 10amps and run a 2000w motor and is small enough to fit inside the old battery box. Worth a punt at less than a tenner.



Edited By William Chitham on 31/08/2019 14:15:00

Edited By William Chitham on 31/08/2019 14:15:39

Thread: Harden Boxford Main Spindle Key?
27/06/2019 13:38:11

Thanks all, I'll leave it as is, it seems a bit of a weak spot in the design though. That key has to transmit all the driving torque to the spindle as well as having to slide back and forth in the keyway and it has no direct means of lubrication. And for some reason it is only about 2/3 the length of the keyway slot in the gearwheel.


27/06/2019 10:57:22

I need to replace the key that locates the sliding gear on the main spindle on my CUD. The old one is fairly worn and it ocurred to me that it might be worth hardening the replacement. I've bought a piece of key steel and I found a post in the forum suggesting the material should harden ok. Any reason not to?

Edited By William Chitham on 27/06/2019 10:57:48

Thread: Historic Frogs
20/06/2019 17:39:42

"Frog he went a courting and he did ride

sword and a pistol by his side...."

Don't remember his name though.

Thread: Electronic Indexers - How Is Cumulative Error Avoided?
30/05/2019 16:07:36

Thanks all, thought there must be more to it. I'd arrived at both the solutions described by muddling around with a spreadsheet but I don't have enough understanding of code to see the sums in the various versions that I've looked at.


30/05/2019 12:22:08

I am planning to build an electronic indexer, initially to make a 127-135 tooth compound gear for my Boxford. Am I right in thinking that the normal way for the programming to work is for the controller to divide 360 by the number of teeth, round the result to whatever number of discrete steps the stepper/drive ratio can manage and apply that repeatedly to the work on the assumption that the error will be insignificantly small? My concern is that the error is cumulative from tooth to tooth and therefore all delivered together on the last tooth. Furthermore the error is proportional to the diameter of the blank. Since I want to cut gears with lots of teeth, a comparitively large diameter and a prime number of teeth to boot the error is going to be enough to make the gear useless. For instance if the error per tooth is .01% then by the time I get to 135 teeth it will be 1.35%. The diameter is around 190mm, circumference approx 597mm so the cumulative error is going to be 8mm. I know many people have successfully built and used these things so I suppose there must be something wrong in my understanding of the principles, can anyone enlighten me?

Thanks, William.

Thread: Hostaform, Nylon or Steel For Mini Mill Gear?
29/05/2019 10:49:17

Thanks Dave, found it., ordered it. I noticed they also do steel replacements for the high low gearbox gears, have you fitted those? I wasn't planning to make a replacement for this although ironically I bought the mill with a view to making metric-imperial conversion gears for my lathe.


28/05/2019 19:12:54

Thanks David, I saw that one and it seems to suggest that Delrin is the strongest but maybe someone has tried the Hostaform in a similar application and can tell me wether it is up to the job. Or else maybe someone could recommend a suppplier for Delrin gears. I need a 30 toothe Mod 1,5. Needs to end up 10mm thick plus a 3mm boss, 10mm bore and a 4mm keyway but I suppose I can machine to all those dims on the lathe if it starts oversize.


28/05/2019 18:32:53

Had a happy day yesterday making my first ever foray into milling with my new to me but rather second hand Axminster mini mill. I had nearly finished making some t nuts when a things suddenly stopped turning. I soon diagnosed the problem as stripped teeth on the plastic spur gear between the motor and gearbox. I phoned Axminster this morning and am waiting to hear from them but don't have much hope they will have the spare so I've been looking elsewhere and seems there are plenty of cheap alternatives out there but which material to go for? Tempting to stick in a steel one but I imagine this gear is a designed weakpoint to protect the gearbox. Delrin I have heard of but I can't find the exact one I want but there are lots selling Hostaform and Nylon 6. Any advice on which material is best would be appreciated.

Thanks, William.

Thread: Oh Dear, I've blown the chop saw...
24/05/2019 17:27:59

Don't entirely discount the possibility of getting spare parts. I broke a small plastic sight glass on an Aldi air Oiler/Regulator a couple of years back. I asked at the store and they gave me contact details for a spares centre which was in Austria as far as I can remember - company is called Walter I think. I contacted them and received a new part free of charge.


Thread: Cast Iron For Boxford Change Gears?
24/05/2019 17:11:40

Thanks for all the replies, all very helpful, the gears are to do imperial on a metric leadscrew Boxford CUD. I do have one of the 54/64 gears from that ebay seller, works ok and nice guy but I have become somewhat obsessed with the whole business of gear trains and am determined to make my own 135/127. I have been using NthreadP to test different combinations and 127/135 it has to be. Aluminium looks nice but v expensive, Delrin looks good for first attempt, I can get enough for three or four blanks for the price of two in cast iron. Still a long way from cutting though as I haven't decided how to do the indexing yet, CNC, or some kind of home brew mechanical. How did you do yours Micky?


Thread: Oxy hydrogen torches
24/05/2019 16:51:31

In the US a lot of bicycle builders are using oxy propane for brass and silver brazing using old medical oxygen concentrators. A lot cheaper in the long run than cylinders and safer too. You can find them on ebay occasionally or Tufnells Glass do new & recon units:

Thread: Cast Iron For Boxford Change Gears?
21/05/2019 12:15:16

I have set myself the task of making a 127/135 compound gear for my Boxford and am considering material selection. I think the existing change gears are cast iron and I have been advised that SG(GGG40) would be suitable. Two questions before I order: can anyone suggest a more economical alternative (some grade of steel plate maybe?) and if it is to be SG what are my chances of getting two 3/8" thick gears out of 1" of round given that I don't have a bandsaw or powered hacksaw?

Thanks, William.

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