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Member postings for David Colwill

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

Thread: New ways to skin a cat
17/01/2021 12:20:37
Posted by Hopper on 17/01/2021 11:02:55:

Looks pretty handy. I have not come across the Rose Index before. I only found one supplier online, Lakeshore Carbide in the USA. $149 for the 2" version MrPete is using. Wow!!!

But it looks simple enough to make one that would do the job.

5c or er32 collet blocks are a good option if you have them. I also use vee blocks for larger stuff but this is limited to 90 degrees.



Thread: NASA testing the limits of engineering again
17/01/2021 09:22:15

Not too ambitious then.

I thought from the title that they might be trying to get them to agree on something! smile p

I must admit, it is good to see them trying to get back to the moon.



Thread: Binocular loupe
14/01/2021 19:42:44


They look like they may be okay but I have no experience of them.

Here is a link to some that are in the UK.

eBay link

At least you could return them if they are no good.



Thread: Linux CNC
05/01/2021 10:39:58
Posted by sam sokolik on 04/01/2021 19:57:49:

BTW - David - what kind of encoder is on the orac?

It has a slotted disc with 48 holes and an index, which seems to work fine.


Thread: In anticipation of the New Year ...
03/01/2021 12:07:47

I'd love to see the out takes of this!

I did notice what looked like one of the robots lying on its back at the very end of the video.

They are certainly coming along though.



Thread: TIG is harder than it looks
02/01/2021 19:01:18

TIG isn't hard, it's damn near impossible.

I bought an R-Tech digi tig earlier this year. I didn't get chance to use it until I needed a small pulley welding on to a shaft. I did manage it but it certainly wasn't pretty.



Thread: Linux CNC
02/01/2021 14:40:54


I have no objection to keeping everything here. It is more than possible that others will stumble across this and hopefully gain some useful info.

As for me I am fairly pleased with the days progress.

I have fiddled around with it and fitted a video card (thanks to the comment by Bayzle) as I was getting sporadic jitter that would flag up an alarm. That has now gone away although the max jitter is 35,000 ns.

I have had another dell which was much lower but haven't tried connecting that yet.

The screw cutting is coming along.img_20210102_141708.jpg

Not perfect but an improvement on yesterday.

It is an M12 x 1.5.

Speed was about 900 rpm.

I spent much less time today faffing around with the interface and it is starting to grow on me.



02/01/2021 10:43:34


The main reason I am trying it is for threading.

Mach 3 uses a single pulse for synchronising Linux uses a multi slot or quadrature encoder.

There are other advantages but I can in no way claim any kind of knowledge about them smile p

Of the other systems.

Mach 3 is great within its capabilities but is getting dated.

Planet CNC looks good and I was tempted.

Mach 4 is expensive and would need a motion control board making it even more money.

Masso is too expensive (for my tastes at least)

Chinese stand alone controllers. If there was a distributor in the UK I would probably have gone this route.

Others will have more to say on these.



01/01/2021 18:45:58


I feel your pain!

I had spent some time trying to find videos on youtube and other info to get me started but couldn't find anything that I understood or felt was going to help, so I gave up. I figured the best way to get started was to play with it and fortunately for me I had help with the initial set up. Even after a short time playing around in Linux I understand more about it but I'm still not sure how far I will be able to go with it. It does seem that there is a catch 22 situation here. If you haven't used it you can't understand anything anyone tells you about it. I know this because some of the videos I watched and gave up on are starting to make some sense now.

I should point out that I only posted this because I know that there are people out there who are interested but are put off by the rather fearsome reputation that it has. I am deliberately not asking for help. I will flounder along for as long as it takes or until I get bored with it. If I can't set it up and run it with information in the manual and already on the forums then it is probably not for me.

That said I have already noticed that I have been very quick to blame Linux for things that were clearly down to my stupidity. An example here is that the speed display (in axis as I haven't got it to work in gmoccapy) wasn't reading correctly. It turned out that I hadn't entered the number of holes in the encoder wheel and it was reading the default value of 100 instead of the actual 48, this made it look as is the displayed speed was half the actual speed and started me trying to work out if it was triggering twice and hence wasting an hour or so until the penny dropped.

I do believe it is worth sticking with as John and others swear by it and it is clearly very reliable once set up. I know that there are other options like Planet CNC, Mach4, Masso etc but they all involve buying hardware and software and you have to take something of a leap of faith and faith is a commodity that I have very little of ( I was seriously tempted by Planet CNC ).

I will continue to fight on but things may have to go on hold for a week or so as I try to get on top of work.



01/01/2021 15:36:26


Happy new year to all.

To answer a few questions.

I am using a Dell Optiplex 330 which has a single parallel port built in. I have several of these running my various CNC lathes and mills and a spare, just in case. I can buy these off eBay for £30-£40 including shipping and should one go wrong I can change it out and dump the original hard drive in it (or a clone if needed) and be back up and running fairly quickly.

I pointed out on the post by Joe that a friend who has used Linux but not for CNC helped me with the install. I will ask him for more info on Monday when I see him.

I can say that I am using version 2.8.1 and have used Gmoccapy 2 axis lathe ( I have a touch screen).

I am using the original stepper motors with Chinese micro stepping drivers.

I have an old diycnc V2.0 breakout board that was kicking around and a spindle board v1.2 made by the same chap that did the breakout board.

The spindle board doesn't work yet.

The motor is a 1/2 HP three phase run by an old Omron inverter which was also kicking around.

I have a Mesa 7i96 but will leave playing with that until I have it all running on the parallel port.

Before I started I gave this process some thought. I decided to use a single parallel port as I would be able to configure Mach 3 to it and this would prove the PC and hardware were okay if Linux didn't work. Also the Orac was bought some time ago just for the purpose of being a test for Linux and so there is no pressure to get this working quickly.

So I have had another play with it today and although I am not much further forward I do seem to be more comfortable with the operation of both the CNC interface and Linux in general.

I have spent most of the morning tweaking acceleration for the motors and have had it cutting more threads. There is something not right about the set up and this will need looking into tomorrow.

I have already had to manually alter the ini file smile p (the first step on the road to mastering Luinux CNC!)



Thread: Rotagrip bore gauge?
01/01/2021 10:50:37


I have used Rotagrip for various bits. They have been around for ages and have always given good service when I have dealt with them.


Thread: Linux CNC
31/12/2020 19:51:54

After much pontification and many delays, I have finally got a Denford Orac running on Linux CNC. I say running but this may be a little optimistic.

The slides move.

The spindle starts (sadly the PWM board doesn't talk to the inverter yet)

The sync and speed pulses work and a solitary (very rough) thread has been produced.

I'm trying to get to grips with the interface at the moment but still struggling with many counter intuitive aspects of it.

I will try to post details of progress as it is made.


Thread: CAM software for CNC Lathes - With C axis and constrained live tool
30/12/2020 18:12:54

I'm just setting up an old Denford Orac on Linux CNC and it is twisting my mind somewhat.

I have a friend helping who has some experience with linux (but not CNC) so things are progressing.

We had the slides moving today but still have to sort the spindle out. Sadly we realised we needed a newer version and are now reinstalling.

I'm going to start with using a single parallel port before setting up the Mesa card (7i96).

This machine was bought to be a test bed for Linux and I was expecting trouble in the initial setup but hopefully will end up with a stable and usable machine.

For all its faults Mach 3 is a doddle to set up and customise.


Thread: Boxford 300 VMCI mill centre
27/12/2020 11:03:14


Whilst I have no experience of the Boxford you mention, I do own a Denford Triac mill with a 6 position tool changer.

I converted it to Mach 3 some years ago and it is a very well built machine.

Mine came from a school somewhere in London IIRC.

It had been shipped out by Denfords but didn't work on arrival. Denfords offered to fix it but there was a dispute over shipping and it was never returned. Total cost new was £26,000 (in 1989 or there abouts).

Many of the school machines were built to very high standards but have seen limited use.

The only CNC Boxford I have seen was a TCL125 and that too was very well made.

The control electronics and software can be a PITA especially with Boxford who seemed to have a reputation of not granting or transferring licences to anyone who is not a school (I don't know if this is still the case but a poke around the forums will give you an idea) Denford have been great regarding access to information and software for older machines. If you look around their website you will find information and circuit diagrams for most of the machines they make and a number of current and ex employees frequently contribute to the forums.

There have been a few Triacs on eBay between £3000 and £5000 but if going down this route beware of scammers!

I am about to move to the darkside (Linux CNC), so I will probably say more about this later.



Thread: The Herbert Lubricar
26/12/2020 12:08:24

For much of this year I have had a friend helping me for a few days a week and it has been a very useful arrangement for both of us (his business has been badly affected by covid 19) and I have had various projects that I doubt I could have managed on my own.

Not having spent too much time in a workshop like mine, he seems to have taken much of it in his stride, with the exception of the chronic lack of space (and I suspect the equally chronic amount of chaos).

When I had to collect a couple of machines that I had in storage, he expressed doubt that they would fit into the workshop (obviously there was tons of room).

Whilst moving the Herbert No1 into its temporary home, we started talking about these lathes and how they would have been used. As we both live in Nottingham, I had said that Raleigh would have had quite a number of capstans running and that I had recalled seeing a photo of a cart for oiling them. I then suggested that I could get one and that as penance for doubting the capacity of the workshop, he could push it around.

I tracked the photo down in a manual and here it is.img_20201226_112058.jpg

I suspect that Herbert probably didn't make too many of these and that pretty much all of them have now been scrapped.

Has anyone ever seen one of these?

Has one been preserved?

If not, does it matter?

Anyway fast forward a few weeks and with Christmas approaching I decided to take my first serious foray into model engineering.

After hours of studying the photo I managed to produce this accurate scale model of said Lubricar

img_20201226_111935.jpgHopefully he will now be able to lubricate himself over the festive period.



Edited By David Colwill on 26/12/2020 12:11:35

Thread: Boxing Day Tidying
26/12/2020 11:05:08


You are not alone.

I'm here trying to get things in order (well as near as I can get) as I am hoping to get a few days to start converting a Denford Orac to linux CNC.


Thread: Mery Christmas Everybody
25/12/2020 09:42:51

Merry Christmas to all!


Thread: Welding Fumes
21/12/2020 07:22:09

Good to here that you are okay.

A company that I do work for has over the last few years started to provide the air fed visors as part of on going H&S requirements. Nobody (including the welders themselves) was particularly keen but now they are a normal part of daily routine.

It has always been my understanding that any metal vapour is bad but apart from zinc on galvanising I have never really bothered with any extraction. That said I don't do much welding but will be more mindful in future.



Thread: Oil proof brush?
18/12/2020 08:28:38

img_20200524_101630.jpgI too had this and took action. I ordered a load of "acid brushes" (I think acid in American is flux but may be wrong) These are a metal tube with horse hair bristles and work brilliantly for brushing coolant.

I do sell them in my eBay shop but in the spirit of Christmas will send a few out to anyone that PMs me (UK only though)



Edited By David Colwill on 18/12/2020 08:34:09

Edited By David Colwill on 18/12/2020 08:36:38

Edited By David Colwill on 18/12/2020 08:37:12

Thread: edge finder speed
06/12/2020 16:32:56

I run mine somewhere between 500 / 800.

I have had a few disasters by going over 1000 (forgetting to check the speed setting) and watching the end of the edge finder describe a rapidly increasing orbit around the spindle.

Fortunately the cheap spring sets sold by Machine Mart IIRC and others, contain suitable replacements.




I now have a Haimer 3d taster, so will try to run this at 0 rpm smile p

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