Boxford Little Giant

Hello All

I have just purchased a Little Giant toolpost grinder and was wondering which is the correct way to use it, I was told the lathe has to spin in reverse to the rotation of the grinding wheel? also how do I find out what the spindle speed for the lathe should be?

Regards

Roy

Hi Roy

Don't know much about them, but Mr Crispin over on YouTube has a couple of videos featuring a toolpost grinder, so you may pick up some info from those.

Rob

This is a link to a copy of a Dumore Toolpost Grinder manual in my Dropbox account for you to download and should help:-

Dumore Manual

Nick.

Edit. This will be deleted from my Dropbox account at some point, to free up some space, but can be added again in the future if required.

Edited By Nick Hughes on 01/02/2023 17:06:33

Does anyone happen to know who sells spare belts for the Little Giant grinder ?

Phil

Apparently the belts are available at

https://simplybearings.co.uk/shop/Belts-Flat-Drive-Belts/c4601_8093/index.html

Thanks Nick got the manual from your Dropbox account.

Free up the space forever and point future requesters here:

https://www.dumoretools.com/operating-instructions

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Lots of Dumore stuff at vintagemachinery, including a 'care and operation' manual:

http://vintagemachinery.org/mfgindex/detail.aspx?id=2020&tab=3

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Details of the drive belt in this thread:

https://www.model-engineer.co.uk/forums/postings.asp?th=115785

Thanks Nick, it looks as though the Boxford Little Giant is that same as the Dunmore Tom Thumb no14A Grinder.

Further to this thread does anyone know the spindle thread on this tool, I make it 1/4*32tpi which seems odd, I used a thread gauge which I believe was in whitworth form.

I also contacted Dunmore who sell the belts but again some size differences, Dunmore have replied and told me the belt size for there 14A is 10.625" by 3/8. the belt in mine could of course not be correct but it measures about 11" by 3/8. They sell the belts for $13.68 and I do have a USA address to ship to for forwarding to the UK so if the size is correct from them I am quite happy to order belts for anyone else who may need them.

So what is the problem?

The difference between 11" on a used belt that could have stretched over time and 10.625" is 0.375". Divided over the two spans of the belt, that is 3/16" difference in centre distance. Is that not within the range of the adjustment mechanism?

I've used and can recommend these guys :-

Belting Online

Hello All

Nick I looked at the link but the smallest size is 300mm, I may call and see if they can do smaller,

DC31k, there is not a problem, I stupidly did not realise until later on that my Grinder may be a later model because it does not have the round motor as the Dunmore does and some of the Boxfords, it has a parvalux motor that is square and a brown spindle casting and green motor colour scheme which may mean it is a lot newer than the round motors, also all of the bolts and threads are metric except the spindle which has been confired on another forum as being 1/4*32tpi, the reason for putting the size is that there may be a difference in spindle centre measures between the round and square motors and of course belt length, I take on board about adjustment but if I order belts from Dunmore and anyone else on here would like me to get them a belt at the same time I at least want to know that the ones ordered are correct.

Tony Griffiths has confirmed that the early round motor grinders were Dunmore and he sells belts made to length for £31.68 for one and the second half price, I dont know if that is plus vat or not but 2 belts are going to be around £50.

Is this a flat belt? If so I've seen people use toothed belts, but inside out.

Yes that is another way but I am told it can lead to grinding pattern problems because the belt is stiffer where the teeth are and more flexible between the teeth, one way around this is to somehow mount the belt on something like a piece of wood turned to the inside diameter of the belt and mount this in the chuck and use the grinder to mill away the teeth to give a flat belt or perhaps turn it down to give a flat belt.

Sorry yes it is a flat belt.

300mm, the shortest they and many other suppliers do is too long and outside the range of any adjustment, iirc it needs to be either 280mm or 290mm. I will check but it might be a few days. There is a uk source (plus there was a German source) much cheaper than Tony Griffiths, something in the order of about £8 iirc, again it’ll take a few days to dig out.

Thats correct 300mm is the shortest in flat belts but for the money I might just get a toothed belt and turn it over and reverse the grinder and put a drum sander in the headstock annd see if I can get the belt down to the 1-1.5mm thickness.

I have just measured the belt on my Dumore Tom Thumb grinder.

It is 260mm [10¼"] long x 9.5mm [3/8"] wide x 0.5mm [0.019"] thick.

There is a bit of adjustment left on the motor slide so I dare say the 10.625" might be OK.

Phil

Edited By Phil P on 02/02/2023 18:57:55

Another option might be a poly-vee belt (non-synchronous). It varies across its width rather than around its girth which would eliminate the above issue.