Member postings for Martin Connelly

For a one off gear it would probably be cheaper to buy a gear, from HPC for example. It often only makes sense to buy a specific size and range cutter if you are going to make multiple gears for example lathe change gears to add extra pitches or TPI values to what is available. The old saying would seem to apply here, don't ruin the ship for a hap'th of tar. What will happen if you use a number 3 cutter instead of a number 2 cutter is that the teeth will be narrower than they should be and also have the wrong profile.

The other option, if you want to go that way, is to make a rack cutter if you have already got a dividing table or spin indexer and a milling machine. I think this is the way Neil did things for some of his projects, but I may be mis-remembering who did this. An unhardened steel cutter will work for a one off or two off in brass and a 20° cutter can be ground from a piece of HSS

Martin C

The 20° cutter is to make the rack cutter.

Edited By Martin Connelly on 29/11/2022 17:52:31

I had another play with ProbeIt, this time before doing anything else such as probing with my usual macros or running any code. The issue seems to be that ProbeIt does not respond as quickly as my macros triggered by clicking a button. This may be due to the simplicity/complexity of the different probing options or macros. I put a spring over the tip of my rigid probe to try ProbeIt and it is clearly over-running after contact. With my macros I can do a fast approach at 330mm/min and get what looks like an instant stop on contact however ProbeIt bends the spring at both a 330mm/min and a 33mm/min approach. This will not be an issue with a probe such as the probe being discussed in this thread which has a 4mm leeway in the X and Y axes.

I could buy one of these probes but the simplicity and low cost of a home made rigid probe seems hard to beat as long as you have a system that responds rapidly on contact and you don't want to use it on non-conductive materials (I pull out the edge finder for such times).

Martin C

The trouble with using a press is that you introduce more stress. Thermal cycling in the future then allows those stresses to distort the material.

Martin C

Have done. He wants me to do a few tests at different settings.

Martin C

Tried ProbIt this afternoon and I have a warning for anyone with a rigid or near rigid probe, don't use it in its current release. I put a piece of aluminium tube in the vice only held loosely as I did not want to make it oval. I decided to try the internal hole probing routine. After the probe has made fast X axis contact with the right hand inner surface it backs off then makes a slow approach for a more accurate contact. Then it does what it should not, it moves towards the material before pulling back again. In the case of my lightly held tube it actually moved the tube in the vice. I also observed it doing the same thing when probing in the Y axis. This is not good and needs to be corrected. I stopped at that point because I didn't need to find it was doing similar things with other probing options and running the risk of damaging my probe.

Martin C

I've looked at my Mach3 macros again and there was a lack of a G91 relative movement code at a couple of places. Now that I have put them in the macros seem to be working as expected. I think in some cases G91 was already set first by another macro running which did not set it back to G90 absolute motion and in other cases the direction of travel was the same for both G90 and G91.

Martin C

You could make one of these as discussed by Joe Pie Mill indicator holder Stephan Gotteswinter also shows how to use one here Edge finding techniques and he has also done a few videos on making one.

Martin C

At work our recommendations regarding torque were that the figures given were for natural finish or lightly oiled parts and for joints using nuts, bolts or studs only. When a lubricant such as molybdenum or graphite is used the torque figure should be reduced by 20%.

With heavily galvanized parts the zinc could squeeze out over time so hot dip galvanized fasteners were never used for critical bolting requirements.

Martin C

The problems are not consistent, usually the macros I have work but occasionally they go gaga.

Martin C

I have had some issues with Mach3 probing macros. Does it come with any software or a link to where they are available? The issues are powering past the point of contact and damaging probes. I see from looking at the blurb for these they only have a 4mm over run limit in XY and less in Z. I have considered putting a magnetic break point in a probe to avoid damage.

Martin C

The capacitor may only be there to kick the rotor round in the correct direction on start up, it may not actually increase starting torque significantly. If so, any suitably sized and rated motor with the same RPM will be a suitable substitute.

Martin C

A quick google and it seems he was arrested just over 4 years ago.

Martin C

Chris, the affect of gravity is to cause an acceleration, the speed referred to is the speed of propagation of gravity waves across a distance which was not specifically stated in the post above. So no issue with the use of speed in this case and an understandable misunderstanding in your case.

Martin C

It was on Blue Peter with John Noakes and was also an article in a Blue Peter Annual.

Martin C

Here is a recent video by Joe Pie where he shows his small part bender in use. It is basically what I was talking about when I said two dowels in a plate and something to push the material around with. It's quite a long video but the tool is just over 22 minutes in. It can be used for different sized parts by adding more dowels as required in unused places on the plate. I don't know if he has done other videos where he shows it being made or explains its use.

My response was also not designed to put people off flagging up interesting videos, but I do think you have to have your cynical glasses on for a lot of these videos. For example, starting a discussion regarding safety in the video's comments will just increase the comment count and encourage the risky behaviour. I'm not sure if linking a video in the forum increases viewing counts but it seems likely. There are certainly a lot of safe machining and manufacturing videos available that are also monetized and I, personally, do not mind encouraging the originators by watching or commenting on the content and so contributing to their income from YouTube.

Martin C

Edited By Martin Connelly on 16/11/2022 11:37:46

It's part of the ethos of making money from these videos, get it done as quickly and simply as possible without making it look like you need special equipment to do it. It's the everyman concept, every man can do this with basic tools. A drill and an angle grinder and away you go. Look, I'll show you how, just watch to the end and make a comment, and like it as well. If you make a video with lathes and milling machines it puts off people who don't have these tools or experience of them or are thinking of getting them. I don't read every post on this forum, I look at what interests me. As soon as you mention something like CNC there will be a section of the forum who will pass over the posts about it but others will be attracted to them. YouTube videos are the same, they are often crafted to maximise income for the originator. Telling people that it is not safe to do it like this or that it is a dangerous process will put people off and cost the originator money. If you start commenting that it is dangerous then all the comments, likes, dislikes and subscriptions add to the money made as it shows people are watching the video beyond the first minute.

Martin C

I've just had a boarding pass for Aug 22 delivered into my email. Either it's an old one that's just popped out of the system due to these issues or it's a scam. I know that pdf files can carry macros and act as a vector for a virus.

Probably open it on an old pad that is no longer used just for the sake of curiosity.

Martin C

Quick and dirty bender for this sized material, drill and ream two holes in a suitable plate and drop in two dowels. Push the material to be bent around the dowels with a suitable piece of straight faced material.

The reality of most engineering is that good enough is all you need. In industry unnecessary ornamentation or finishing processes are just wasting time and money when making something functional and you only do it if the customer wants to pay for it. It is the principal that seems to be used when a lot of hobby machinery is made. Making something that needs to look good or needs to last also makes it expensive. For hobbyists where time is not costed we can do what we like and if that includes working to very fine tolerances, scrapping off a functional part because we don't like some small defect or going for a mirror finish on every surface then that's for our personal pleasure. I believe someone making a tool like this is aiming for some monetization for their video so working good enough and looking good enough is all that is going to be required of it. It may go into a scrap bin as soon as the video is finished.

Martin

Blondihacks used a DeWalt portable bandsaw to make one. It's not a YouTube video I have watched so I can't comment on it.

Martin C