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Member postings for Mark Davison 1

Here is a list of all the postings Mark Davison 1 has made in our forums. Click on a thread name to jump to the thread.

Thread: Burnerd Multisize EC Collet Chuck - replacement KEY
09/11/2020 22:42:58

Checking my ebay purchase history i bought a K4 from rotagrip for exactly the same job. I seem to recall i had to sleeve the spigot, but teeth are correct.

Thread: Huanyang VFD help please
08/11/2020 22:17:39

The pot is easier to set up

08/11/2020 20:45:41

Donyou have the instructions. They will tell you which menu settings and which terminals. The settings will be different for momentry buttons vs switches. Ive done it recently. I assume it differs by model. Mine was a cheap AT1 (£60).

Thread: Harrison mill - metric lead screw form
06/11/2020 17:35:23

Thats a good point, can anyone with an imperial machine tell me the pitch of the Z axis?

05/11/2020 20:16:35

Thanks for the replies. I'm in the process of converting the machine to CNC with stepper motors and ball screws. I'll post progress to date on here soon.

I want to keep all the original bits so it can be put back to standard should a i or a future owner so desire. The existing bronze nut for the Z axis is very worn and I was thinking about adding a new one to my list of 'projects'. It would be the first lead nut I've tried to single point thread so was wondering if I'd get away with the closest ACME insert (6 tpi is close to 4mm pitch) or if id have to gring a HSS one (i don't have a boring bar that will take HSS bits). Based on the last reply I may chance my luck and buy a 6TPI insert and see what the profile looks like (the existing screw is 1-1/8" dia, 4mm pitch, single start).

04/11/2020 07:42:58

Does anyone know if the leadscrews on the metric version of Harrison's milling machines are ACME or trapezoidal?

Thread: Straight edge for checking the slide ways on my mill's knee
25/10/2020 23:05:33

You clearly spent a lot of time on that grinder, great work.

I intend to play safe and only tickle small areas with a scraper if it is obvious that I'll improve things. The saddles get a bit tight at either end of its travel and im hoping most of that is caused by wear on the narrow flat ways under the knee. I think it is 0.035mm based on the mic readings. I don't want to go anywhere near the top surface of the knee and certainly not the v! I'm not feeling that brave at the moment.

Edited By Mark Davison 1 on 25/10/2020 23:05:50

25/10/2020 18:48:23

Nothing on evilbay at the moment, other than a pair of 12" long chesterman parallels, which would do at push but they are £90 posted (with some surface rust). Ive seen cammel back castings but need something ready to use.

I'm thinking I'll have to buy one of Chronos' 400x400 granite surface plates and sit it on there upside down on 4 1-2-3 blocks to allow for the v. That way I can use a dti on my scribing block. Becoming a bigger job than I'd expected. My current surface plate is only 8"x12" so not big enough.

25/10/2020 17:43:50

I'd wrongly assumed all 4 sides would be ground, but apparently not I found this on the interweb. Even the thickness doesnt sound very accurate

Thickness +0.05/-0mm
Width +0.2/-0mm
Length +5/-0mm

25/10/2020 15:14:31

I've got the knee off my harrison mill and want to to check the wear on the ways, in particular the narrow ones on the underside. Where can I get a 12" straight edge to apply the blue to? Alternatively any ideas what i can use as an alternative, e.g is gauge plate flat enough? Measuring the side without the V suggests there is some wear in the middle but I'd like to check that the wear is only in the bottom face.

Thread: Standard steel tube sizes vs bearing sizes
25/09/2020 08:46:53

Turns out I've assumed the extensive range of sizes offered by M-Machine aren't exhaustive and there is a 2-1/8" x 1/4" wall that would suit. Just need to see if there is some where local I can find that size now.

25/09/2020 07:41:07

I want to make a tool post mounted gringing spindle for my lathe. I have a 6" long ER20 spindle with a 20mm shaft. The obvious bearing options are 7204 (47mm OD) or 7304 (52mm OD). My question is, why do all the standard seemless tubes (for the body) come in sizes that are largely incompatible with the bearing OD?

The standard sizes either have an ID so large it would only leave a 1mm internal shoulder to butt the bearing against (55x45mm tube), or the OD would only allow for a 1.5 or 2mm wall around the outside of the bearing (2" OD tube) Im trying to avoid using solid round bar (say 55mm OD for a 47mm OD bearing) and having to turn most of it into swarf.

Thread: Hoffman dividing head
01/09/2020 22:13:16

Ignore the small off centre hole in the top of the 2nd part down. I had to drill that to knock the remains of a broken locating pin out.

01/09/2020 22:03:55

Pinned and pressed

20200901_220219.jpg

01/09/2020 21:06:04

I have one and dismantled the same bit earlier this year, for a different failure though. Does this help?

20200901_210135.jpg

Thread: Mill power feed & controller
23/07/2020 22:42:01

Thanks, I will do. I have several arduinos and Teensy 3.2s, so i think ill be giving this a go. I need to ouyput to much bigger stepper drives/ NEMA 34 motors, but I assume I can do that (5v or 3.3v pulse/dir signals will drive them)?

23/07/2020 16:49:09

What is the controller, is it something like an Arduino? How does the phone app interface, via Bluetooth. I'm after something like that to tide me over until I get linuxCNC running on a raspberry pi.

Thread: where to buy a good open morse taper 4->3 sleeve
17/07/2020 21:05:01

MadMike - the spindle is true and the OD of an MT4 dead centre i have also runs true when in the spindle. I even went as far as wrapping the MT4 dead centre shank with 2000 grit wet and dry and rotated it in the spindle bore to make sure there were no high spots.

Keton - I've bought from all 3 of those I named, and will continue to do so. The vast majority of purchases have met my expectations and in general that's what i have come to expect. I have also had cause to return a product each. In two of those cases (one of which was ARC - embarrassingly wonky T-nut and stud) the product should never have passed a basic visual inspection, the other (not ARC) would have been picked up if it had been checked for square at the factory (a center finding square, so it should have been). This was one of those rare occasions where i was prepared to pay a premium price for a branded product to give myself the best chance of getting something spot on first time. I didn't mean to cause offence, but i can only speak from my own experience. I've not bought from MSCDirect and my have wrongly assumed they sold branded equipment as well as unbranded import.

16/07/2020 21:14:03

Thanks for the rota grip link. Definitely MT4.

16/07/2020 20:22:48

It is for the spindle of a Colchester bantam, reducing it from MT4 to MT3 and needs to be open endedto allow a drawbar to pass through. My current one is from RDG but I've discovered it isn't concentric so I'm loathed to chance RDG/ARC/Chronos. Bison seem to do them (**LINK**) but I'd rather order from the UK. I've tried cromwell, cutwel and MSCDirect and they don't have them on their websites, any idea who might sell a branded one?

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