Member postings for Martin Hocking

Wow! Thanks everybody, once again this forum has proven to be a mine of useful knowledge!

So much more of a comprehensive response then I could have hoped for. Starting with a fairly theoretical query about how motors work best, I seem to have most of the other things I have been wondering dealt with too.

I think as has been suggested I’ll have a go at digging out the star point on the original motor then, I’m always game for a bit of a tinker, and as Steve pointed out there is certainly no shortage of people here who know more then I ever will!

Incidentally thank you very much to Steve for chiming in because I think I got to page 26 of a forum search for ‘motor’ before I gave up looking for his thread after John fletcher mentioned it!

Thanks to William for the link to the brocott website that looks like its got everything I’m going to need. The motors on my mill are both Newman motors so hopefully my motor will have some similarity too.

Hopefully I’ll have some success and then I can see how I get on with the motor as nature intended and go from there.

Thank you so much to everyone, and watch this space (or one nearby!)

Martin

Thanks for the reply’s everyone, very much appreciated.

John: Am I that concerned with efficiency?

Erm I thought I was…having a bit of a look about at motors it seemed that getting the most efficient motor without spending silly amounts of money was the best bet. And having seen how motors seem to be listed with a fairly broad hz range I started to wonder if that could be exploited. But in a slightly perverse twist I thought that if the old motor had enough oomph I could use it to convert my myford/Drummond m type lathe to variable speed. Pretty much disregarding the emphasis on motor efficiency! I think it’s a slightly toxic mix of waste not want not and frugality that I blame on exposure to MEW at a relatively young age!

Clive/John: Your both absolutely right it would be really good to rewire the motor to delta. Clive is right, it is hard wired so I will have a bit more of a look into that, to see if it’s something I can do myself or perhaps a local motor rewinding company can do for me at something that doesn’t make my wallet cry!

Out of curiosity I did purchase a cheap energy monitoring socket, to see how many watts (roughly) the motors on the machine draw at different hz and I was very impressed by how the inverter pulled a fair bit less than I was expecting. It’s totally unscientific but the inverter was pulling more or less half the juice at 25hz than at 50hz. Which would certainly which go to back up what you were saying about how good vfd’s are at managing how much power motors use.

Nigel: I’m glad you’re here, I think your certainly partly to blame for this thought experiment rabbit hole I’ve fallen down haha! I read the similar remarks you made about your machine on another topic about omnimils. Having played around with the vertical head and an indicator, it definitely needs one of the stiffening piece you and others have made. Just to clarify your remarks, when you say you think that 1.5hp is a minimum, do you mean to fully make use of what the machine can do or to pull the skin off a rice pudding?

cheers

martin

Hi there chaps and chapettes,

I don’t post very often but this place is my go to when I’m looking for advice from a grown up and I usually find what I’m after has already been asked so thanks everyone!

I’ve finally got my elliott milling machine up and running, I’m using the original motors which are wired for 415v. The vfd I have bungs out 220v. The horizontal motor seems to work well enough like this but the vertical motor won’t pull anything higher than the lower speeds (about 500rpm).

So once my kids stop needing all of my money (I can dream ha!) I’m going to get a new motor for the vertical head.

My question isn’t really specific to the machine though. I understand that motor efficiency is measured at full load. Does this efficiency at full load relationship continue as you go down in hz? So a motor that is 80% efficient at full load of 1hp at say 50hz would that still be 80% efficient at full load at 0.5hp at 25hz?

The reason I ask is that I am contemplating using a 1hp motor in place of a 0.75hp throttling it back with the vfd and adjusting for lower speed with the pulleys most of the time. Essentially with the view to save electricity. It seems motor efficiency per £ seems to jump up quite a bit at the 1hp mark.

Sorry if this is a bit garbled and equally sorry if I’m being daft.

many thanks

Martin.

Thanks everybody, like most of the model engineering community I'm rather adverse to the idea of spending any money so I'll have a bash with the porter cable ones.

i'd like to get some er collets in a larger size like 32 for some more useful work holding on the lathe but the router collets will still be useful for holding a few small slot drill end mill type stuff in my little spindle.

Thanks again.

martin

A friend of mine is an engraver for a sign manufacturer. After I recently asked if he had an er11 collet I could look at (thinking of making a little spindle), gave me some food for thought because after showing me both an er11 and er16, he showed me a box of slightly unusual collets in his cupboard. He asked if they might be of use to me and said that I could have them if I wanted.

Naturally I was pretty chuffed at the prospect but I need to figure out if they're are going to be usefull to me or not. They look like this:

Each one has its own closing ring circlipped to the top. From what I can gather they are porter cable collets for use in wood routers. I can see making a little chuck straightforward enough, I may even be able to use one of those soft morse stubs you can buy. One thing that does interest me is the relief (black bit in middle if relief isn't the right word )in the middle if the collet. It's not a double angle type so I don't see what having the gap does. Any suggestions?

So what do people think could I use these for a small mill drill spindle for my lathe?

cheers

martin

As someone who would class themselves as a beginner , even after several years of playing around with my lathe and bits of metalwork. I have found this thread very interesting. So much so that I registered so i could post a reply.

i think it's a shame that David has received a bit of a pasting as has been mentioned, his series has potential to be something good. However I think this sort of series in a monthly magazine will take such a lot of time that it will be very hard for a majority of newcomers to make use of it. Not to mention the fact that if you are a newcomer able to afford a lathe then you can probably afford a book by Sparey or hall which will get you going.

I think the magazine is still a good read which really depends on your interest some months will be better than others. The real problem that mew has is that there is a wealth of information out there on the web which is easily accessible not to mention a good 100 years of good ideas in the me/mew's past issues.

What I'd like to see is a bit more stuff on modern developments, I found the outrunner drill an interesting read perhaps a bit more of a discussion of what outrunners could do would have been interesting.

As far as beginner series go I think, a problem solving feature every month a bit like the old me letter pages were. Where someone has aproject but isn't sure of exactly how to do it or has got stuck. I.e. A bit of tricky work holding, and an experienced swarf monger could help in person, then it could be made into an article. A little bit like calling in the a team!

I like the short snappy tips idea that would be great and really useful. I think even I could contribute then!

cheers

martin