Member postings for MW

Perhaps this would be a better, cheaper alternative for a single speed pinion operation, plus all the experience you would gain from making this hemingway pinion mill? ive got a fair few old motors lying around and would be ready to hook one up?

http://www.hemingwaykits.com/acatalog/Trent_Pinion_Mill.html

The trent pinion mill

Yeah i definitely wouldnt want it as a vertical mill, it would be really annoying.

the sixis one oh one certainly looks the business for horizontal milling, the width of the T-slotted table is splendid and spindle distance is far greater  i guess its just a bit of a rarity to actually find one for sale.

Edited By Michael Walters on 25/11/2015 21:06:10

http://www.axminster.co.uk/axminster-engineer-series-su1-universal-mill-505104?gclid=COOfksurrMkCFacewwodOBUCbQ

I looked at this mill because it looks like quite an attractive bench-top machine, the only one i've seen that allows you to use it as a horizontal machine, which is the main draw.

I believe its actual name is SIEG SU1 but axminster sell it as their own version.

Is it any good and would anyone consider selling it second hand? then again if its that good youll want to keep it i guess, duh :P

I concur with this, It's exactly what i'm going to do and press fit some ball bearings inside, i'll turn the insert for these using a boring tool on the lathe (around 22mm with a depth of 7 or 8mm?) and mount the housing with socket screws, making sure to align the housing with a bar/shaft in the apron, it should increase the area the shaft has to rest on, and in turn help maintain the alignment .

Michael W

Hey guys, little update for you,

I went into the workshop this morning and thought i'd give my prototype one last try before improving it, with hoppers advice of changing the gearing so that the handwheel is using the largest and the pinion shaft is using the smallest. I wouldn't have believed if you told me that such an error of simply having the gears the wrong way around would make such a dramatic difference. It actually worked! with very minimal pressure required.

It still has its niggling little errors such as the amount of movement "out-of-round" on the pinion shaft and the fit around the handwheel collar, but this is really all nothing considering how bad it was, i meant it literally wouldnt move unless you proper forced it to do so. Its fair to say that this will simply be a matter of cosmetics, what i'm most happy about is that i can put all that effort into making these problems just right without needing to worry about the soundness of the mechanical principle, it really can be done on a clarke, regardless of the offset to the saddles centre point!

so its safe to say that the good people of ME.co.uk have saved my bacon, i wonder how long, if ever, it would've taken me to figure that one out. I may have even just simply accepted defeat and gone back to lame old permanent leadscrew engagement :P.

I will eventually post what will become the finished article, equipped with half nut (provided i dont need further advice for that too!). If they take this thread down i'll post a new one with the finished one.

A big thanks to all ,

Michael W

Hi People,

It's great to see how many people are pitchin' in their two pence about this, i really didn't expect this amount of response to a rather obscure modification. So thank you very much for your advice and compliments.

I'm thankful you have pointed out to me that the gearing is the wrong way around, i suppose if the handwheel was trying to move the pinion too fast it would be liable to slippage rather than steady engagement. I have the aforementioned article in the recent MEW but i will give it another look over.

It's interesting how John has noticed that their isn't many dovetail beds around with a rack and pinion feed, and something i completely overlooked and the leverage imposed by the off set distance could be a problem, with moving the rack closer to the bed being a last resort, i would struggle to find a suitable spot, so i will try to strengthen the support of the pinion mechanism by extending the apron to squeeze in another side so that the pinion can be supported from two points like an arbour.

I am also considering milling some keyways and replacing the dodgy pinion shaft, as well as increasing the size of the bearing area, its only 10mm thick aluminium which would allow a long shaft to wonder out of position quite wildly. this could be done by turning some collars which can be fixed to the holes in the plate to distribute the bearing load.

Its always handy to point out the obvious and yes, i have removed the leadscrew nut before trying this! haha, I haven't come around to creating a half nut yet, which will be a struggle in its own right, but i have bought a replacement feed nut to use this as my project piece, that way, there wont be any trouble trying to create a left hand acme thread. More importantly, if anything goes wrong, i still have the original, the whole thing can be converted back to its original state, a very important design consideration, absolutely no permanent change if its not worth the risk!

The jibs have also been losened too, again, its not a silly thing to add because some people might overlook this, the bed could do with a good oiling though, it hasnt add one in a while and it could do with one to make it easier to heave.

So i obviously have alot of work to do before i can turn this from an experiment to a finished article, its more than i've ever taken on before and its not going to lie down without a fight but i hope i can inspire others to try this and you have certainly given me hope that it might work.

When youve got to make things yourself and you dont have a step by step, youve got yourself in for a "stumble-by-stumble" , you can quote me on that.

I'll keep this thread updated with comments and photos til i have put the coffin nails into this challenge.

Michael W

Thank you all for your comments,

I have created some pictures using my phone, which i hope will allow you to see what exactly it is i'm looking at.

This is the machine

This shows how the rack connects with the bed; its bolted down with these specially made posts, to the right you can see the rudimentary framework for the apron at the moment

A top down view of the hand wheel and the gear compound connecting the pinion to the rack, you can now see how the pinion shaft is only supported from one side.

This is a close up of the aforementioned gubbins

So you can see where i'm going with this when i say i think the distance offset by the cross slide, the play on the pinion and the lack of a rigid support for the shaft might just be a major contributor to my ceasing problem? If anyone had any novel or outlandish solutions, i wont be offended by them.

Michael W

Hi,

I'm new to this website, but i have chosen to join now as i have a significant problem that i'm not able to solve without the help of some more experienced engineers.

I have a medium sized lathe, the clarke cl430, that uses a traditional leadscrew nut as a linear movement, although this has its benefits, its pretty slow to move the saddle back and forth between turning and drilling operations with the tail stock.

My solution to this was to apply the same system that other lathes use which is a rack and pinion to rapidly traverse up and down the bed, just like on industrial machines. Of course, this is only achievable if you dis-engage the feed nut from the saddle and use a half nut, that's a problem for another time though.

So far, i have obtained a suitable 1.0 module rack and 20 tooth pinion and mounted this flat to the base, this wasn't ideal, as they are normally located directly underneath the bed but space wasn't permitting, so it had to be mounted tooth side up, if that makes sense.

A thick aluminium plate has been bolted to the cross slide/saddle to make up the apron for which the hand wheel sits on and i have chosen to gear the hand wheel to the pinion shaft, as is also traditional. flats have been made on the shaft to situate hold down screws, i'd rather use key ways but i don't have the finances to buy the broaches for that.

I have mounted these components to the machine and the hand wheel is almost dead stiff, i cant move it without being really forceful with it and the table feels very heavy to shift up and down. I've taken a step back from it to try and analyse the situation, i'm hoping i can fix this.

First of all, the engagement of the pinion shaft to the rack on the machine isn't ideal; the rack isn't quite level and so the tooth engagement isn't the best. There also isn't any form of support on the other side of the shaft, so it's only supported from one end by the apron.

The gears and shaft also revolve slightly out of true which seems like a bit of a tolerance build up.

I'm seriously questioning whether even if these problems were dealt with, would the table just be too damn heavy to move with a pinion? I think maybe the main cause for concern is the fact that the pinion is only supported by a single shaft.

I would be very thankful for any useful feedback, i'm sorry i cant provide any photos immediately as my camera is playing up, thank you for reading.