Member postings for Martin Connelly

Tony, when replying there is an icon at the top of the reply box that is a globe on a bit of chain ( looks like a blue bubble on some wheels). When you hover over it it says link. Click on it and it brings up a small window that should be easy to fill in with your link (link URL) and anything you want to call it in Display Text.

Martin C

Dave, do what I do and blame it on autocorrect. You put RPS and the stupid autocorrect changed it to RPM

Martin C

I think the powers of 2 micro-stepping were used because it is an easy thing to do with off the shelf ICs. Plenty of binary dividers/multipliers to choose from. If you design a system from scratch it is not hard to use the same system as used for a VFD where any frequency can be used from the minimum setting to the maximum setting of the VFD. Just set up suitable values in the driver and the switches to select them.

I think any modern driver with the correct voltage and current capacity will drive your stepper motor.

Martin C

Where I used to work I had skips full of waste cut offs of stainless pipe and tube. The 1" was 16swg, about 1.6mm, wall. This makes me think that this should be readily available. If you wanted to you could make a couple of support plugs for the end and turn the outside down to a suitable wall thickness. You should be able to make a suitable split collet type support to hold it all round and bore to the wall thickness you want if you want to keep the 1" diameter. You can get a substantial boring bar down a 1" tube.

Martin C

Edited By Martin Connelly on 16/01/2023 12:43:42

I have found the rounded end on some steel rules does a good job.

Martin

As Roy suggests shim stock would be a good start and then laser or water jet cutting into blanks for further machining should keep it flat. If doing it yourself consider a Dremel type tool with thin cutting disks to cut into useable pieces. just don't let it overheat in order to avoid thermal distortion.

Martin C

What we used at work for vertical surfaces or short distances was a Wyler electronic inclinometer. It gave its readings in millirads which for small angles can be considered to be mm/m. For rotating shafts we used Pruftechnik laser based Rotalign kits. For horizontal distances for getting machined surfaces in the same plane or at the correct vertical offset we used a self levelling dumpy level with vertical scales held on the surfaces with magnetic bases from Brunson Metrology. With the dumpy level and the scales we could get far better levelling than with a precision inclinometer as we could get the difference in height over a number of metres down to less than 0.1mm. It was easier to achieve the levelling tolerances with the dumpy level and vertical scales.

The alignment of rotating shafts connecting two machines had to take into account thermal growth of the equipment so was often set up with odd angles and offsets over significant gaps (which are very hard to measure with long support arbors and dial indicators fighting gravity). Once we started using the Rotalign laser equipment it became much easier as you could enter the type of alignment you wanted to do and the angles and offsets you were aiming for. You also entered the dimensions of the flanges, their distance apart and the distances to the supports to be shimmed. The equipment then told you how much to shim each support by and how much to move the supports horizontally to achieve your required settings. After a confirmation check of the alignment you could then print off a report sheet for the quality records.

Back in the 1980's we once had about six draughtsmen and design engineers on the shop floor trying to figure out what the sag due to gravity was in a long arbor and what the measurements were telling us as a result. They were trying to do it using many sheets of graph paper and spent a whole day on the issue. Happily I was not involved because at times it got a bit heated. It was this sort of waste of time that allowed my department to justify the cost of laser alignment equipment for initial manufacture, testing and on site assembly and sign off. Time is money, especially when working in the middle of nowhere and often in some far off country.

Martin C

Hopper, the steel used for a SHCS is chosen for its toughness and is then heat threated to upset and form the head followed, after it is cooled, by roll forming the thread. The steel is never really chosen to be easy to machine and it has a lot of its internal grain structure distorted by the forming and rolling processes. This produces a quality socket head cap screw that is fit for purpose as long as that purpose is not (as many of us know) to be raw material for something else.

Martin C

When I was at work and we needed one I ended up buying a selection box of about 100 types as it was cheaper than sourcing one but as a company we only bought things from a few selected suppliers. Ebay on the other hand have plenty. Try a search for BSP grease nipple and you will find lots of thread sizes including UNF and metric as well as BSP

Martin C

There is a tick box for opting in or out of this, I have mine set to send me an email so I also get the notification, but I don't know what the default is for new members.

Martin C

Here are some screenshots showing the error I found in Ezilathe, there is the original DXF page, the Ezilathe simulation and the Mach3 run page showing the actual path produced.

I would also say that the Mach3 wizards as supplied are not perfect. I had to redo some of the facing wizard script due to faulty coding that had, for example, minus signs where it should have had plus signs. If anyone wants the corrected script let me know, it is just a short script so not a big file, I could probably post it in here if required.

Martin C

I don't know what the latest version of Ezilathe is but version 1.7.3.0 had some problems when looked at. It messed up radius calculations which would result in scrapping my sample file part when on the last few passes. It calculated a 2mm radius curve with a 1mm Z change and a 2mm X resulting in the tool going outside the profile and into the workpiece. It should have been 2mm for both X and Z. It may not seem like much of an error bit when you are deep into a wide groove the side of the groove would contact the tool over a large area.

Martin C

I do some parts with Lazy Turn which is part of the Mach3 family. It imports DXF files but the file should only be the part outline above the centreline and does not require a line for the face next to the chuck/collet/headstock. It is limited in some of the things it does so is the least used option. I did something today just using Notepad to write a file for a profile which is easier for some simple things. The other thing I use is Mach3 wizards. I have modified the screens so that the Manual page has the four wizards I use most, turning, facing, boring and tapers, picked with one of the usually unused buttons at the bottom of the screen. This improves the functionality of a touchscreen as well,

If you want to keep a file from a wizard you just chose to edit the file and then Save As to a suitable location and with a suitable filename. Saved files can be put together in Notepad to create a more complex part. That is what is going to happen with the small file I wrote today, it will be put on the end of a facing wizard file so that the complete program will remove the bulk of the material with the section from the wizard then do the fiddly bit with the extra part I created.

I use AutoCad for drawing DXF files and any 2D cad program will do this including some versions of AutoCad that were given away free as magazine cover disks (as long as you have an old XP system to run it on).

Martin C

I have used "Ivory 133" cast acrylic for a cosmetic ivory look.

Martin C

You have not specified material being cut or the size of cutter you are using. I would add to the earlier posts by saying that if you are cutting aluminium or one of its alloys then you do not want to use coated cutters, only polished ones such as HSS with a nice shiny finish. The other thing to consider if you are removing a lot of material is a carbide insert end mill to remove the bulk of the material before changing to a sharp HSS end mill to finish to size. I also agree with earlier posts that you need to be sure you are always cutting and never rubbing when using an end mill. You should be creating well defined chips and not dust or fine needles of waste.

Martin C

I used to walk over a railway bridge on the way to school when I was under eleven years old. The line was electrified for the local trains but occasionally there was a steamer going under and you got the smoke and steam all around you. An unforgettable smell. On one side of the bridge was the local station and I when I was very young, just past being a toddler, I was on the platform with my dad when an express steamed through on the near line. I was terrified.

Martin C

John, I always had similar thoughts about the Authorised Personnel Only signs that cropped up regularly. I argued that anyone can deem themselves authorised in their own mind. The same goes for competent without some definition of what is meant by competent.

Martin C

There are two Joe Pie videos on YouTube called:

Machining ultra thin shaft spacers and precision washers

How to Hold and Bore Out Thin Shims

These may give you useable ideas.

Martin C

If you have ever seen the results of fitters using a large drill's morse taper as a hammer on the blunt end of a drift to release another drill from a machine's socket you would know they are far from hard.

I have turned a point on some steel held in a collet then (carefully avoiding the sharp point) put the 4 jaw over the freshly turned centre. That way I can mount an irregular or large diameter workpiece between centres and drive it by lightly gripping it with the 4 jaws. Most recently I turned some Ø110mm acetal pushed onto a mandrel in this way. No way to do the part with a drive dog even if I had one big enough, you can't get enough grip on a mandrel with plastic and you can't glue it as you can't heat it to release the glue.

Looks a bit like this old one (3) Facebook

Martin C

Ingenious and engineer both have the same linguistic root.

Designers often have a poor understanding of manufacturing methods, costs and possibilities.

There is always something else to figure out and sometimes sleeping on a problem will solve it.

Martin C