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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: Milling on a Lathe with a Vertical Slide
02/05/2021 11:49:04

Can't help with specific attachments for your lathe, but do consider HSS cutters - they are more forgiving of the lack of rigidity inherent in a lathe milling setup. After initially being blinded by the multiplicity of cutter options and then promptly snapping a tooth off a fancy specialist carbide one I decided to road test a 10mm stub length HSS cutter in the lathe. It works a treat. IIRC it was from Drill Service Horley.

02/05/2021 11:04:09

If you lack a collet holder then chuck a pece of bar end roughly double the diameter of the cutter in the 3 jaw. Make a punch mark to align with No 1 jaw, tailstock drill to the cutter diameter and then remove and make a saw cut opposite the punch mark. Then your cutter will be repeatably concentric. Worked for me as a stop gap until I had a collet holder.

Thread: Help wanted, How can I use a stepper motor as a table feed.
18/04/2021 18:14:09

You will probably need something beyond a CNC shield for a 3.1A stepper, The CNC shield takes plug-in driver modules of various kinds (e.g. A4988, DRV8825). They do the same job but their current capability varies.I think 2A is about the max though - the form factor probably precludes anything more.

To source 3.1A you probably need a separate driver which will likely have screw terminals rather than little square pins.

Using a lower current driver won't fry anything - the driver will limit the current but it may not provide enough stepper torque to do the job,

Sorry I'm not au fait with the higher current drivers because my smaller machine is OK with the little ones but hopefully someone else will come along to advise,

Control-wise you indeed could go for a microcontroller running GRBL but I don't think GRBL can support much of a control panel because input/output pins on the Arduino Uno are mostly needed to talk to the steppers. Sorry I'm not sure what hobbyist controllers and firmware can do this but maybe someone else can suggest something.

EDIT: typo

Edited By Andy Carlson on 18/04/2021 18:16:15

Thread: Faircut Lathe Advice
07/04/2021 22:04:52

I have one of these. It is not a sophisticated machine but I like it a lot.

Vintage wise, I think mine is just pre-WW2. The one in the pic appears to be later because it has vee belts but the Faircut 'Senior' is still a pre-war design. As you have no doubt read elsehere, 'condition is everything'. Check for backlash in the cross slide and leadscrew feeds. Expect some though - this lathe will be no spring chicken. The leadscrew is 8TPI and the cross slide 12TPI, so compare to that.

Compared with other lathes the big omission is a half nut. That doesn't stop you doing anything but can slow things down and does cause more wear over time on the leadscrew and nut. On the plus side the bed is longer than, say, a standard Drummond 'M' type of similar vintage and that is a good thing to have - even if the job isn't long it's nice to have some 'elbow room' to move the tailstock out of the way.

At best it only has a dial on the cross feed handwheel... which may or may not be resettable. Prewar lathes have fewer dials.

It is worth checking the exact height between the toolpost 'shelf' and centre height - this determines the size of the cutting tool that can be used. The compound design changed over time and the toolpost looks non original so measuring is the only way to tell - mine has 12mm. I don't think you'd want less than 3/8 inch.

To fit a new chuck you will need a backplate to mount it to the spindle, which means reclaiming one from another chuck or making one. The important bit is the spindle nose thread which is 7/8 BSF on mine and likely the same on the one in the pic. You are unlikely to find a backplate to buy like this so it's reclaim one or make one.

The asking price seems high. I bought mine 18 months ago in a superficially rusted state but with a hatful of accessories for south of 300 quid. I've seen plenty go for less but usually without a lot of tooling which does make a difference.

If you search for 'Faircut' on here you will find two threads about Faircut 'Senior's, one of them mine. There is also Brian Morehen's thread but he has a Junior which has quite a few differennces.

That's all I can think of for now. Happy to answer any other questions.

Thread: Buying advice sought re Milling Machines: e.g. Proxxon: FF230 vs. BFW40/E vs. MF70
01/04/2021 08:58:45
Posted by John Smith 47 on 01/04/2021 02:55:53:


@Frances IoM
TBH, this all sounds way beyond me.
What's a "DTI"?

A very useful thing!

Dial Test Indicator, sometimes just Dial Indicator or Clock Gauge. Used for checking that work is parallel to the axis on a milling machine, concentric on a lathe and so on. I have a small lever style gauge on a magnetic base and adjustable stand. I use it all the time.

There is also the plunger style gauge. I have one of those too. I keep intending to arrange clamps to hold it parallel to my lathe axes but never got a round tuit.

The MF70 is not magnetic. I've added a couple of bits of 4mm steel plate between the XY table and base on mine so that the magnetic base has something to stick to. Other folks have made clamps to attach one to the spindle housing.

30/03/2021 08:07:27
Posted by John Smith 47 on 29/03/2021 23:43:44:

I do all kinds of random DIY project & innovations, and every project is different.

It's difficult to predict which jobs will come along but my experience has been that I have not found a need to use the MF70 for domestic projects. My Unimat, Cowells and the Faircut 3 1/2 inch lathe on the other hand have all been put to use in this way. Work has included a new brass button fur our old style doorbell push (maybe 3/4 dia), new buttons for the cooker hood (the old plastic ones disintegrated) and several things with threads on the end to adapt or extend various things.

Whatever machine you have you will find yourself making tooling on the machine, for the machine. I've probably spent more time making tooling than anything else, but with four small lathes and the MF70 that's probably my own fault.

Whatever machine you have you will also find that there are jobs which are too big for it. With 1mm sheet I would expect that Y travel will be a place where you will quickly find the limits. My own experience with small modelling jobs on brass sheet is that I quickly wanted CNC so that I could do accurate diagonals and curves etc. I've done this and it has been successful... but that's a whole other tangent.

I won't attempt to say much more on the subject of spindle speeds. I don't pay a lot of attention to what is 'correct'. I do pay attention to nasty noises. The MF70 speeds are OK for 1mm-3mm carbide milling cutters and drilling 2mm and below. The higher speeds are very handy with sub 1mm drills. Yesterday I was doing 0.3mm holes transversely in 0.5mm brass rod on the MF70...but there are plenty of occasions when I'd like to go lower than 5000 RPM but I can do that on the lathes.

Do consider a lathe but XY travel will not be a strong point there - the usable vertical travel of a milling slide may be less than half of the height of the work mounting face.

29/03/2021 22:43:06
Posted by John Smith 47 on 29/03/2021 21:25:40:

TBH, as a novice, I'm feeling slighly out of my depth on all this.

Being able to cut mild seel is the entire point of my having a milling machine. But if I can't readily lift the machine off a table, maybe I should bale out now!


Andy - Could I drill mild steel at 2mm with a PROXXON MF70? Realistically what do we think the maximum diameter of hole that I should be able to drill mild steel with?

I've milled mild steel on the MF70 and would nave no concerns about doing it again. It won't chew metal off at a rate of knots but it will do it. The job needs to be small otherwise it will take ages. Steel swarf from carbide cutters is like thousands of tiny needles so bear that in mind if you plan to do this in a domestic setting.

In terms of drilling I don't think I've ever had a need to drill mild steel on the MF70 because I have other machines. When the MF70 was my only machine I did drill brass and aluminium with 2mm and 3mm holes. It coped with both but the noise was pretty nasty with a 3mm drill. A nice sharp drill and a slower speed machine is a much nicer experience.

3.2mm dia is the maximum the unmodified MF70 will hold. If converted to ER11 then it will go bigger but bigger drills are also longer and the high speed will be even more of an issue.

At the end of the day the MF70 is a small scale modelling machine and this is a model engineering forum so you won't find many folks expressing love for it here but like I said... within its limits (and those limits are small) it is OK.

But honestly, if you want to drill 6mm holes in steel then it's not the machine for the job.

Thread: Whicht "Fonts" were used on th e Somerset & Dorset Joint Rlwy??
29/03/2021 20:06:15
Posted by Mike Paling on 28/03/2021 11:32:51:

Hi Andy ... thanks for your quick reply.

I have just checked the HMRS web site and the most recent back copy available is the March 2019 edition ... and it is shown as being out of stock anyway.

Any ideas on how I get the "latest version"?

Mike

Hi Mike. It's Vol 23 No 10 - March 2021. 5 and a bit pages on SDJR loco lettering, partly observations based on a drawing in the care of the HMRS, partly correspondence with one of the preservation folks and partly relying on photos which can be had in books like the old SDJR loco history (David and Charles).

Sorry I don't have a good answer short of joining... other than find a friend or else try contacting HMRS and asking nicely.

HMRS also do well regarded transfers in 4mm and 7mm. Not sure whether they cater for bigger scales TBH. I model in 2mm and they don't go smaller than 4mm.

Regards, Andy

Thread: Buying advice sought re Milling Machines: e.g. Proxxon: FF230 vs. BFW40/E vs. MF70
29/03/2021 18:31:56

The MF70 is fine within its capacity. I use mine for 2mm scale modelling and many other 2mm modellers do too.

It can be converted to use an ER11 spindle but the high minimum speed of the drive is another limitation. I know folks who have addressed that one too, but then you are getting quite far from the original machine. As you know, the axis travel is a further limitation. If you want to drill up to 6mm then I'd say it isn't for you. I can't speak from experience of the other options but rigidity is crucial to a mill so any increase in space for Y or Z travel should also be accompanied by an increase in the bulk of everything that keeps the head positioned with respect to the table.

Trouble is... the price point goes up pretty sharply too.

Thread: Whicht "Fonts" were used on th e Somerset & Dorset Joint Rlwy??
28/03/2021 10:51:20

Try to get hold of the most recent HMRS Journal - there is an article on exactly this question.

IIRC he concludes that the main influence was the MR lettering from Derby... some new SDJR locos being painted there. He could not be definitive on the question of shading colours. There were also variations - most likely the lettering was done by signwriters working to written instructions or perhaps copying an example so variations may be down to the individual's interpretation of the instructions. The buffer beam lettering definitely varies considerably between locos.

Thread: Single Phase Switch + EStop?
02/03/2021 13:34:51

I've used RS part 398-5279 . It is a panel mount NVR switch.

It has a connection for a second external E-Stop button - if this connection 'sees' a closed circuit then the NVR power can be switched on. If anything (like an E-Stop switch) breaks that circuit then the NVR switch will trip to off. You could (should you wish) wire multiple E-Stops in series on this cricuit and then any one of them would trip the NVR off.

Being panel mounted, you need to make sure there is no access to the gubbins at the back - including the E-stop circuit which also carries mains voltage.

Thread: Arduino CNC
17/02/2021 22:41:57
Posted by An Other on 17/02/2021 14:52:51:

One thing that I have since realised is that GRBL on the UNO has the capability to drive three axes...

Another interesting variant I played with is the Sparkfun Turbo UNO - this runs at 48 MHz, and has many capabilities beyond the UNO

There is a bunch of stuff going on to make use of more recent microcontrollers and/or drive more axes. No doubt a good deal of it is 'bleeding edge' but if you want more than 3 axes or capabilities that won't fit into the memory on an Uno then it's worth looking around to see if anything 'out there' suits. For example...

https://www.routerforums.com/threads/grbl-hal-what-ive-been-doing-lately.141693/

Thread: Flexispeed- Change Gears
09/02/2021 13:53:01

The above discussion seems to have a lot in common with the Cowells.

The Cowells set is 20T to 50T in steps of 5T, with two off 30T for achieving a 1:1 ratio.

The Cowells also has two permanently assembled compound gears - 16:32 and 20:56, mainly for slow feed although 16:32 has its uses for screw cutting.

The Cowells gears are 32DP. I'm not sure of the correct pressure angle but I've added some 20 degree PA delrin gears from HPC and they work OK once the centres are opened out to the right size and a keyway added.

If you want to make up your own compounds from the Cowells change gears then there is a challenge to overcome - you need a keyed idler bush and the 3/8 bore does not leave a lot of diameter to play with... essentially the key needs to be part of the bush because there isn't really room to cut a keyway in the outside of a bush.

The other limitation with the Cowells is the space available on the quadrant. This may make some of the higher numbers of teeth less useful than you might otherwise think.

I've added 37T and 47T (also from HPC) to mine for doing BA and imperial approximations. The inspiration came from this thread...

https://www.modelenginemaker.com/index.php/topic,1020.15.html

Hope this helps. Some of the above may apply to the Flexi but I know that some of them have a different drive arrangement for the feedscrew. The Cowells is a 1mm feed screw pitch, not sure if your Flexi feed screw is imperial or metric.

Thread: Arduino CNC
25/01/2021 19:58:20
Posted by Ronald Morrison on 24/01/2021 11:59:51:

Thanks to Ady1 for posting a way for experimenting with the A4988 with one stepper motor. Could you see using that to control a rotary table or an indexer? How about just the x axis on a mill or the leadscrew on a lathe? Maybe it would work for the cross slide. Hmm... how about two of them, one on the leadscrew and one on the cross slide to work in a coordinated fashion to precisely fashion odd shapes?

Maybe! The AccelStepper library includes the MultiStepper class to allow you to move two or more steppers in sync with each other. It can also drive Unipolar steppers (via some power transistors) if you have a need to use the ultra cheap 28BYJ geared steppers that were made for moving air conditioner flaps. If you want to do something out of the ordinary and are happy to write and test the code then AccelStepper is great. If you want something you can send G code to from your CAM tool then it isn't.

25/01/2021 19:33:42
Posted by Ady1 on 25/01/2021 19:20:37:

I've just realised I'm using the 8825 and not the 4988

my head hurts

I doubt it will make a massive difference. The basic behaviours and pins are compatible. I think the 8825 can handle slightly more current and maybe do a bit more microstepping.

If you really want your head to hurt then look at the various Trinamic TMC series driver boards from Waterott - again the same basic design and at the simplest level you can replace the 4988 like for like but wayyy more settings to mess around with.

Thread: Help with Tilley Lamps
25/01/2021 17:41:40

New mantles are not as good as old ones... but using thorium is frowned upon nowadays I believe. This may be part of your issue - new ones are less bright and more 'warm white' in my experience.

However if you have pulsing then it's not the main problem, but I guess 'a little' is open to interpretation - they probably all do this to some extent between a barely noticeable fluctuation in the sound at one extreme and going completely out at the other.

You've already changed the vapouriser which is the usual answer to this issue so I think I'd be tempted to try some other paraffin - it's probably the least effort next option... and even if it doesn't solve the problem it will get used eventually. My last lot was Bartoline from 'Go Outdoors'... if they are still going in the current situation...

Thread: Arduino CNC
25/01/2021 08:58:26

I'll chip in my setup...

Proxxon MF70 with home made stepper mounts and NEMA 17 motors

Arduino Mega 2560 running Marlin with Protoneer (ish) CNC shield carrying A4988 stepper drivers

Universal G Code Sender from a branch with Marlin support

G Code either done manually or using dxf2gcode

The NEMA 17s drive through flexi couplings to cups which fit over the handwheels. I think the flexi couplings are important for avoiding missed steps with NEMA 17s. Other folks have resorted to NEMA 23s.

I wanted hacklash compensation which sent me down the Mega route. GRBL on the Mega can do backlash compensation but can't be configured to drive the IO pin permutation required by the CNC shield. Marlin can. It's a bit odd for milling but it does the job.

Dxf2gcode is OK for profiling around 2d shapes but lacks sophistication beyond that. The main branch lacks pocket milling capability but there is an experimental branch for this (which I have not tried).

There is some interesting looking newer stuff around that can use for example the Teensy board instead of Arduino. I haven't got past reading about it yet because basically my setup does what I need most of the time, the occasional shortfall being mainly in the CAM department rather than the CNC controller.

Regards, Andy

Thread: Flexispeed meteor-II lathe Cross-Slide / lead-screw specs.
22/01/2021 22:59:43
Posted by Johan Viljoen on 22/01/2021 17:56:01:

I'll keep at it. thanks for all the input so far

Well done.

If you haven't tried it then I'd still recommend measuring over wires. It will give you a bit more info, it's a better check than measuring the OD and it's not too difficult to do -.just find something that is a consistent diameter and in the right ball park, The sweary man from the Admiralty who taught me how to do thread cutting recommended using chopped up paper clips for the job we were doing. That was for a different sized thread so they may or may not be in the right ball park for your job.

20/01/2021 19:20:42
Posted by Michael Gilligan on 20/01/2021 08:45:53:

(a) The difference would also be between 3/16” and #10 diameters ... small, but non-trivial

(b) May I ask : what ‘misfit’ do you see shown in a photo of a single item ?

A... yes, I was using bigger sizes where UNC and BSW have the same nominal size

B... I was assuming that the deformation of the end-most threads in the photo was showing the misfit. Maybe that wasn't right?

I dug out my drawing again. It was just done for my own amusement some time back and never intended for sharing... or even necessarily for me to remember the full detail later, but...

unc-bsw.jpg

Checking the dimensions again, this is for an 18 TPI thread with UNC in blue and Whit in green - the colours were less muddy until I exported to JPEG. This assumes zero tolerance (which is never the case). The male side is at the bottom. UNC chops off the peaks of both male and female threads as shown by the lines on the drawing.

After doing this I decided that trying to determine UNC-ness or BSW-ness of an unidentified thread by fitting it to a known nut or bolt was probably not going to be very informative with real world tolerances in play.

Hopefully the OP is making progress.

20/01/2021 08:10:24

I'm surprised the fit is that bad if it is just a UNC vs BSW difference. When trying to identify some threads a while back I drew up the two forms overlaid on each other. Yes their angles and treatment of the thread peaks and troughs are different but...

1. I think it's very difficult to tell either by looking or by measuring which one is which

2. When trying off the shelf nuts and bolts together they seemed to all fit each other, both ways of mixing.

Off the shelf nuts and bolts can have a generous tolerance allowance which may account for point 2 and may be less true for your lathe parts but hopefully you get my point.

That's not to say it's fine to mix them in critical situations - one is 60 degrees and the other 55 so the thread flanks won't apply load to each other evenly... but in the majority of cases they do seem to fit together.

To me, UNC vs BSW doesn't add up to the amount of misfit that your photo shows.

I don't have any speific knowledge of the threads on the Flexi but if I were you I would also check the measurement over wires of the male thread before going any further - it may not fully resolve the question but it will be a measurement of the thread that you are dealing with at the part where it needs to engage with its friend. The link below will tell you the wire size and measurement over wires...

https://www.cgtk.co.uk/metalwork/reference/screwmeasurement

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