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Member postings for Andy Carlson

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

Thread: Lathe drilling attachment
12/01/2022 19:15:48
Posted by Henry Brown on 12/01/2022 10:42:29:

Just curious, what stops the chuck from rotating when milling/drilling other than putting it in a low gear which presumably still allows some movement due to backlash?

Good question. On mine I have a couple of options - one is to add a washer to a thread cutting gear stud so that the gear won't turn. This does still allow some backlash. It also allows me to use, say a 60T gear on the spindle marked up with a piece of chalk to do dividing.

The other way is to put the drive belt onto the biggest pulley - then the lathe spindle has a mechanical disadvantage over the motor...

Neither way is perfect but usually get the job done...

...but for the higbee job I needed to turn the chuck by hand while milling so locking it would be counterproductive.

12/01/2022 08:34:52

Another option... a Potts spindle with an MT1 ER16 holder from China (with drawbar) and a belt drive. Traditionally these things were driven from a line shaft above I think but few people have those now. I made a sleeve from a bit of PVC drain pipe so that I could clamp my Unimat SL motor bracket onto it. Having the motor this way round helps with the overall length but is clearly not helpful with clearance/visibility around the job. It works though. In this pic I was using a small carbide milling cutter to higbee the start of an internal thread.

I've also used a cannibalised flexi drive to make a toolpost drilling attachment for my little Cowells lathe. The drive motor (drill) can then be well out of the way. The flexi drive bearings would not cope with milling though.

p1070520.jpg

Thread: Proxxon mf70
05/01/2022 13:31:26
Posted by Ches Green UK on 05/01/2022 09:26:56:

I did replace the bearing washers with ball race thrust bearings shortly after I bought the MF70. This Russian chap explained it all https://www.youtube.com/watch?v=EvgeMu2dYps

(Edit: This German chap has a lot of interesting mods ... https://www.youtube.com/user/mtoynet/videos )

Thanks for the vids. I think I'd been put off by the Russion voiceover in the past but muted it and the subtitles explain it pretty well. I had originally planned to use a thrust ball race myself but I had some PTFE sheet in stock so I used that and it worked.

05/01/2022 08:57:10
Posted by Ches Green UK on 05/01/2022 01:22:47:

The Z axis has a bit of slack but if you remember to tighten the lock it's managable.

I had the same issue with mine - getting on for 1mm of play. I've sorted it now - I had to make a box spanner to get at the nut that is recessed into the plastic at the top of the column. Adjusting the nut would probably be enough to sort the play but I also found that the plastic dial was rubbing on the neighbouring boss and the two were wearing each other away so I took the handle and dial off and made a 1mm PTFE washer to sit below the handwheel and take the thrust when the Z axis is being raised. It's a lot nicer to use now.

04/01/2022 22:30:14

I have an MF70 and like it but if drilling is your primary objective then I would look elsewhere. The collets will hold 3.2mm maximum diameter and the spindle speed is high so anything over about 2.5mm results in a horrid squealing noise because the lowest speed is still too high.

I mainly use mine for milling parts for 2mm scale models and it does that very well.

Thread: Autocad and Creo Free Equivalents?
30/12/2021 15:19:52

+1 for QCAD. I moved to it when DraftSight became unfree. DS is an AutoCAD clone and QCAD is not so it took a little while for me to find out how to do things quickly in QCAD.

The free QCAD only does DXF. If you have DWGs that you want to use then look up the free ODA file converter.

Thread: Unimat sl1000 tool post tool holder
16/12/2021 20:00:31
Posted by Howard Lewis on 16/12/2021 17:38:24:

(That's how my Turning Instructor made his cigarette lighter when he was a Capstan operator, apparently )

What brand of cigarettes were they?

(Sorry!)

Thread: CNC Engraving
08/12/2021 08:33:35
Posted by Ray Lyons on 08/12/2021 07:11:38:

Thanks Andy. Now that opens up a number of real possibilities and renews my interest. Could be I will have a new toy for Christmas.

No probs. Do read the other threads about the MF70 if you are thinking of going down that route though - it is a small machine and will only take small cutters and do small sized work. CNC conversion is a project in itself.

If you want to do nice serifs like Jason then you need to eliminate any uncertainty in the 'Z' direction - that means dealing with backlash, making sure the job is held properly flat and also having smart enough software to drive it. I have not yet aspired to those levels - most of my work can cope with a a tenth or so of a millimetre of uncertainty in 'Z'.

07/12/2021 22:24:45

I've done some simple engraving of plastic name tags on my CNC controlled MF70 mill. There was a thread last year where I was asking for advice about cutters, plastic and so on.

For small machine dials I've also had some success using photo etching (by PPD in Scotland) to make a 10 thou thick nickel silver dial which is then rolled and closed up using a simple lap joint. The core of the wheel is made to be a snug fit inside the dial with a groove to make room for jointing splint. In this case I was lazy and arranged the diameter so that the circumference was exactly 100mm. It's only really viable if you need some other stuff etched and have some spare space on the sheet though.

p1080193.jpg

Thread: Is Model Engineering "green"?
30/11/2021 19:10:11

I've been trying to resist... but temptation has got the better of me.

An eco variation on what must be everyone's favourite recurring forum topic...

Presumably more green points should go to those who populate their workshops with lovingly restored classic British made lathes rather than newly minted ones from the other side of the planet.

Thread: DraftSight no longer free
28/11/2021 12:29:02
Posted by Perko7 on 28/11/2021 06:51:52:

so I need something that will allow me to still access the collection of dwg files I have created over the years.

A lot of the free CAD tools handle only DXF. The ODA file converter will allow you to translate your DWG files into DXF... even after you lose access to your original tool.

https://www.opendesign.com/guestfiles/oda_file_converter

It is possible that the conversion process messed up my fills and that neither QCAD nor LibreCAD were to blame. I did not dig into the detail because it was easier to just draw the problem ones again.

28/11/2021 11:48:18

I tried LibreCAD briefly. My reason for doing so was that I'd just stopped using DraftSight and had found that QCAD was having issues correctly drawing a fill (or hatch maybe) in a drawing that had been originally created by someone else. DraftSight had handled it ok but QCAD messed up the order of the vertices so the fill was all wrong.

LibreCad also messed up the fills on the same drawing. It was as bad or worse (I can't remember exactly) so I carried on with QCAD and redrew the affected fills.

I believe that the drawing was created originally with AutoCAD so this may have some relevance for you.

Thread: QCAD/CAM
18/11/2021 13:51:24
Posted by Michael Gilligan on 18/11/2021 10:24:33:

Based on the notes here: **LINK**

https://sourceforge.net/p/dxf2gcode/wiki/Installation/

… I’m tending towards QCAD/CAM as my optimal solution

[ and will just have to hope there are no ‘gotchas’ ]

Yes the Mac installation does look rather techie. It's easy on Windows unless you want the bleeding edge changes.

Do let us know how you get on if you go for QCAD/CAM.

17/11/2021 22:24:16

I can't answer your question Michael as I use just QCAD myself but I am interested in the discussion.

FWIW I use dxf2gcode to do G Code generation. It is fairly basic but helped by some careful layer naming (tool diameter etc) it has got me up and running. It's OK for profiling and has recently had pocket milling added but probably falls a long way short of some other CAM options. All of my stuff is on Windoze but the web page says it works on Linux and Mac too.

Thread: Advice from the photographers.
27/10/2021 21:52:43
Posted by Nicholas Farr on 27/10/2021 15:43:34:

Hi Andy, as I tried to point out in my post, <snip> but thanks for your input.

Edited By Nicholas Farr on 27/10/2021 15:46:16

Sorry, I didn't spot that you weren't the OP so I was mixing up your slide collection with what Nathan had said earlier. Feel free to disregard

27/10/2021 13:03:43

Glad to see you are experimenting.

If Kodachrome forms such a small proportion of your collection then I would not overthink it TBH, just do the best you can and concentrate your thinking on the slides that form the majority of the set.

Some of the scanner options change the way that the image is captured - ICE dust removal does an infra red pass for example. Some options change nothing about the actual capture but are instead using built in postprocessing steps in the software. My own preference would be to get the capture as good as possible (sharpness, resolution, exposure etc) but avoid the built in software steps because I would be willing to do these myself and play with the settings using my own choice of software (Darktable usually) but if you want less effort and are happy with the results then stick with the steps in the scanner software.

Maybe you are doing this already, but have a good quality blower to hand - something like a Giotto's Rocket and shift as much dust as possible before scanning.

26/10/2021 08:43:13
Posted by Nathan Sharpe on 25/10/2021 23:43:56:

I know I have a Canon lens 35/80 modified for Macro. I've never used it but will try to understand the set up and use.

If you would like the paperwork that came with the lens I'm happy to send it.

TBH I'm not sure what I could usefully do with the paperwork. Most of my conclusions have come from experimenting with lenses using a steel rule where the side would be, checking focus in live view and measuring the sensor plane to slide distance and how many mm of the ruler were actually captured. Bear in mind that what you see in the viewfinder may be less than you get in the final image (not sure if the same is true of live view).

I have applied some 'O' level physics when comparing different focal lengths and deciding what else to try but it's fairly rough because camera lenses have multiple elements... for some reason we did not cover 6 element lenses at 'O' level

Macro lenses are optimised to produce a flat subject plane at close working distances so are a good bet for that reason. That doesn't mean that other lenses won't work though.

There are some lens tests online at **LINK** which may or (more likely) may not cover any lenses that you have. If not then you (like me) are back to experimenting.

Many of the lenses tested are not traditional camera lenses and need more effort to adapt but it does rate the Nikkor Micro 55mm highly, both the f2.8 and f3.5 versions. The Nikkor goes to 1:2 on its own and 1:1 with a 27.5mm extension tube (PK13 or M2) so you would need the extension to get 1:1.6. If you are adapting from EF then you also have the option of using EF extension tubes instead of Nikon ones, it's just a question of where you put the adapter. The exact length of the tube is not super critical for what you want but the lens focus graduations wil only read correctly for that length.

On the whole though, try not to get too bogged down in specs and theory - keep it as simple as possible, try a few things out and see what produces good or not so good results.

24/10/2021 23:28:12

VueScan should work with the OpticFilm - I use it with mine (8200i). Scanning will be somewhat slower than using a camera... although when you factor in the time to set up the slides and do the postprocessing I doubt it makes a huge difference. VueScan is paid software but not super expensive and you can try before you buy.

I've moved to a home made rig using my DSLR now, mainly because my OpticFilm did not cope well with shadows on Kodachromes. A crop frame DSLR is probably the worst starting point in terms of finding a lens and camera to slide distance but it can be done.

A lot depends on what lenses you can lay your hands on - don't rule out adapting a good quality manual focus macro lens - a Nikkor Micro 55mm plus an extension tube should work well. Ironically old Nikon lenses can be adapted to the Canon EF mount and still focus as intended without extra glass... old Canon lenses cannot.

Kodachrome is notoriously tricky to scan because the dark areas are very dense. For the same reason many guides say that IR dust removal will not work (but some disagree). On the other hand it is reckoned to age far better than any other slide film - certainly my Dad's old Boots slides have faded horribly.

Thread: Flexispeed Lathe
14/10/2021 13:56:07

It's worth investing in a M14 x 1.5mm tap or two from Tracy Tools. I bought just the plug tap because I use the lathe (Cowells) to most of the internal thread and then use the tap just to finish the thread. If you don't want to thread cut then probably best to buy a second cut tap too.

Do the thread as one of the early operations and then mount the job on the spindle to get everything else nice and concentric.

I am lucky to have most of the original factory chuck options but have made an ER16 collet holder for my lathe.

Thread: Randa lathe has me much confused
13/10/2021 23:07:34

If your lathe uses a grub screw to disengage direct drive then it probably has a small flat on the spindle. You should turn the pulley so that the screw will line up with the flat before tightening it. The snag is of course that you can't see the flat but you can experiment to find the point where the screw will tighten down furthest. Often the flat will be in line with a more visible feature on the spindle such as a keyway but no promises.

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