Member postings for Martin Connelly

If it's only to get the lathe working then it does not need a long life so a 2mm wall will last long enough to make a replacement at some point.

Martin C

It occurs to me also that if the pulley can be mounted on the end of the shaft and the motor positioned to suit you do not need a through bore so the wall thickness can be increased.

Edited By Martin Connelly on 03/10/2023 18:20:53

Do the online definitions include roughly cut or sized? That's how I always imagine a billet to be. So faces that are not flat or have been flame cut or rough cut on a saw for example and certainly not to exact dimensions all round.

Martin C

Any chance of fitting a plug then using a 2mm or 0.04" drill through to take out the bulk of the material first, as Jason pointed out you did not state how long the bush is. I have done long keyways on the lathe as Jason suggests but it took a lot of passes at each setting to clear out the slot. The problem is that for long slots a tool with too much rake digs in and overcuts but a tool with too little rake deflects the tool enough to skip over the surface after a short section of cutting.

Another method is to make a bush as is used with broaching cutters and then make your own cutter from HSS. I think I have a 3mm broach but I would have to make a suitable bush for this bore but I think a home made one to suit your inch sizes may be possible.

Martin C

I cracked one in school closing down a rivet on a test piece where I wanted to avoid hammer marks around the rivet.

Martin C

Doesn't WD40 contain waxes that will congeal over time?

Martin C

The problem with wear is twofold. Excessive wear of the ways will result in the tool moving away from and towards the spindle centre of rotation as the carriage goes over worn sections of the ways. It takes a lot of wear for this to show up. The more subtle problem with wear is that if the force needed to move the carriage along the ways changes it is possible the carriage can twist in the XZ plane to varying amounts as the force changes. If it is this twisting that is causing the problem then levelling the bed will probably not cure it. This twisting is more likely to show up with lathes that have a narrow carriage. My lathe is 170mm across the ways but the carriage is 280mm wide along the bed. Looking at some of the lower cost lathes they seem to have carriages with widths that are much closer to their distance across the ways.

The geometry of this twisting is that the further away from the centre of the twist the cutting point is the more it will result in non parallel cutting. The way this distance can vary with how the lathe is being used makes it hard to track it down, it's not always possible to put the cutting point close to the centre of carriage rotation.

Martin C

You could download and use Estlcam for free, it has a nag page with a duration that goes up by about 1 second per part you produce a program for if you use it as shareware but for a few parts it is a minor inconvenience. It will allow you to import a DXF and produce the tool path for any size cutter. As Jason says, a smaller cutter than the internal radius would be a better option.

Martin C

Bolts with a metric thread, Whitworth, Unified, Ba etc. are screws, machine screws as opposed to wood screws, self tapping screws or other specified types of screw. So some screws are bolts, but not all of them

A coach bolt is a bolt that may, or may not, have a machine screw thread. So not all bolts are machine screws.

Sometime a bolt is considered to be a machine screw with a section of plain shank, but not always.

Are you still confused? It's the mongrel nature of English vocabulary that means such words are used with poor definition.

Wire gauges have increasing numbers for smaller sizes. I have read that this reflected the number of time the wire was drawn to reduce its size, might be true. If you then make small screws from wires with these sizes then it could be argued that that is why small screws follow a similar convention to wire gauges.

BA threads ore different though. The basic size 0BA is a metric thread of Ø6mm and pitch of 1mm. Each size smaller reduces the diameter by a factor of 0.881 and the pitch by a factor of 0.9. So if you want to calculate the size of any BA thread of size n then you can use 0.9^n for pitch and 6*0.881^n for diameter (rounded to 2 decimal places).

Martin C

Edited By Martin Connelly on 26/09/2023 18:32:27

Just to avoid confusion I would like to point out that travel along a lathe's bed is usually the Z axis and travel of the cross slide is usually the X axis. This results in the Y axis being vertical. I think Neil L is looking at it like a vertical milling machine where the X and Y axes are horizontal with the Y axis being front to back but a lathe is more like a milling machine on its side.

People who use CNC on a lathe would use this usual orientation for a lathe but people who are manual users only are not likely to have picked up on this convention.

Martin C

As well as books there are some useful tutorials on Youtube.

https://youtu.be/tkEVwpl2S4Q Titled Thread Anatomy, explains some of the terms used for threads and shows the most common thread forms.

https://youtu.be/smExyKMfiIE Titled How to Measure and Identify Bolts, explains TPI and pitch and use of a thread gauge.

There are others as well but getting a good understanding of these concepts would probably have helped you figure out where your problem with the flanged nut and the tool post was.

Martin C

There is at least one (short) video on Youtube showing ball end mill sharpening.

https://youtube.com/shorts/aekWZX_JYLk

May be helpful

Martin C

If you don't have thread gauges then a standard M10 stud or screw will have a 1.5mm pitch. If you have one you can check it against your unknown thread like using a thread gauge to see if it is also a 1.5mm pitch thread. An M10 thread will not match an 18 TPI imperial thread form.

Martin C

I think it should be possible to use a piece of RHS or RSJ as a starting point to make your own. It should be possible to add a couple of stiffening ribs held in place with screws if needed and then you can skim the working faces with the milling head. Add an aluminium fixture plate and you are done. If you use a plain piece of aluminium you can put in threaded holes for clamping down the vice and add more as needed for other parts. Extra plates for other uses are going to be relatively cheap. If you add a few dowels to the base you can make the plates interchangeable.

There are also a number of used cast iron cubes to be found if you look at ebay with sizes like 6" x 7" x 9" which may be a good option as well.

Martin C

Edited By Martin Connelly on 22/09/2023 12:59:48

Tony, there were some mechanical digital readouts that were fitted to the handwheels before modern electronic scales became cheap enough to be considered value for money in a home workshop. These mechanical readouts would still be at the mercy of backlash and error accumulation.

It seems that, for most of us now, when we see DRO we automatically assume it means an electronic one with scales mounted on the ways. I do think the original post by Martin K implied this type.

Martin C

The majority of words that have the Gibraltar pronunciation of g are of French Origin. I went to school with someone whose surname was Gibb pronounced as in gibbon. So I wonder what the origin of the word is, is it from French or is it from someone's name? Maybe that would give some insight. Try Susie Dent, she likes this sort of thing.

Martin C

Thread cutting is all about ratios between the spindle and the leadscrew. If you have a metric leadscrew that is set to rotate 1:1 with the spindle you will get a metric thread. If you have an imperial leadscrew set to rotate 1:1 with the spindle you will get an imperial thread. The intervening gearbox just changes the ratio rather than the measuring system.

Martin C

I bought one like the blue one for use at work. It was only for putting a dumpy level on to raise it off the floor to the level of a benchmark on a large fabrication and for that it worked fine. As this use did not require that the platform be level or able to take large loads or stay parallel to the base at all times I was happy to buy the cheapest off the shelf item available. The cost of designing and making something to suit in a factory that had hourly cost rates going from £40/hour upwards meant off the shelf was the best option.

Martin C

In my youth I worked on Saturdays in Lewis's department store. I remember checking the possessive 's used like this and found out that if names ended in s this was considered to be correct.

Martin C

On the opening screen pressing keys m, a, t or d will take you to the Manual, Auto, Tool or Diagnostic screens. In the manual and auto screens pressing q will take you back to the opening screen. On the Tool and Diagnostic screens there is a blue arrow next to the Reset button, this takes you to the Auto page. These few buttons and key presses mean you can move from screen to screen quite easily.

If there has been a change from feed in mm/min to mm/rev then this can be changed back to mm/min by entering G94 in the MDI input window. Change to mm/rev is done by entering G95 in the same way or by having it in the Gcode program. This is often the case when the Gcode is for thread cutting, there is a G95 instruction but not a G94 to return it to mm/min. I suspect that this is what is happening to you. I think you also need to be in mm/min mode to jog if the spindle is not rotating.

Regarding jogging, is the Jog On LED green, if not click on Jog On, is the Jog Inc. LED green if not then click on jog mode to change from continuous movement to jog. If you are on the Auto Cycle screen after the Gcode has run then you need to use the blue arrow button to the left of the Cycle Start button to return to the previous screen with the jog selection buttons on it to do this.

Alternatively if you toggle the jogging screen you will be able to change jog mode and also see a few keyboard shortcuts on some of the keys, these also work when the the jogging screen is hidden. You can toggle Jog Mode by using Ctrl J on the keyboard if you do not want to change screen. And Alt J changes the jog distance setting.

One other thing to note is that I have had the occasional seemingly random problem of the Slow Jog Rate on the jogging screen reset to 0% and this needs to be raised to a rate that suits your machine. I suspect there is some keystroke combination that acts like the rate lowering button that can be accidentally pressed. The first time this happened I spent a lot of time finding what the problem was.

The index pulse caused me some problems when I tried out a different controller. I used a generic board that picked up the index pulse and also showed it working in Mach3. Trying everything to solve the problem of threading not working I reverted to my original Smooth Stepper (I had used it to get CNC working on my mill) and that cured the issue of threading not working. The reason behind the problem is that when using an external controller Mach3 uses the external controller to trigger the motion for threading. This means that the Smooth Stepper works as it is designed to do, threading using the index pulse. The generic board did not work as it did not have the built in ability to wait for the index pulse to trigger the threading motion. The point here is that for threading using Mach3 with an external controller is that the external controller must be capable of working with the Mach3 system otherwise you will be struggling to find a problem that is due to an unsupported board. This is a case of asking the right questions before buying a board. It is not well documented and I found this out by asking a Mach3 group. You need one that explicitly states that it is Mach3 threading compatible or that the vendor says is compatible. That way you have grounds for a refund if it is not compatible. If you still have the Smooth Stepper board I would use it on the lathe.

Martin C

Edited By Martin Connelly on 19/09/2023 08:58:25

Edited By Martin Connelly on 19/09/2023 09:10:10

I have used Machscreen to modify the screens for Mach3 Turn to suit my needs. I put new buttons on the manual screen in place of the blank ones at the bottom of the page to take me directly to the wizards for turning, facing boring and tapers. I also modified the button that posts the code to take me directly to the Auto screen after it is posted. I have a manual data input line on the first Auto screen as well and used the blank space on that screen to add a button to go to the turning wizard.

I have corrected an error in the facing wizard, see the current thread regarding fitting an ELS.

Martin C

Edited By Martin Connelly on 18/09/2023 18:26:25