I have never had problems getting polyvee belts in the UK. I have not actually purchased belts from 'simplybearings.co.uk' but I have bought bearings and other parts and they gave an excellent service. (no connection etc)

In my opinion the article had too many similar photographs but a bit vague on some details.

I did notice, is that the method of installing bearings shown does risk potential damage to the new ballraces. Apart from the the fact that the peice of angle iron the writer used could bend, picture 41 just made me cringe as the inner race is unsupported so all the force neede to seat the shaft is being transmitted through the ballrace itself.

When installing bearings in shafts and housing its is important to apply pressure ONLY to the inner or outer race (whichever is the relevant press fit) so that at no time is any axial force applied to the balls or track surfaces.

A plate (washer) of substantial thickness that bears on the inner and outer race is also acceptable as its unlikely to dish more than the axial movement in the bearing.

Ian

Edited By Ian Phillips on 28/03/2013 12:05:11

Hi Ian,

It's unusual to get constructive criticism on articles from readers so I appreciate your post. Praise is nice; questions are thought provoking; rude comments are what they are! – honest opinions like yours are helpful!

The reason for using angle iron was I thought it would be less likely to flex.

I have to apologise for making you cringe. The forces involved in drawing the spindle into the bearing lke that were actually quite modest, not much more than a push fit, ceratinly not enough to be called a press fit – don't forget the inner race has to be able to move slightly on the top end of the spindle to allow you to adjust the preload, and the bearing seat at the bottom end of the spindle was no tighter. I did describe the 'gentlest persuasion' needed to remove the old race. In contrast, the outer bearings are an interference fit in the housing. Perhaps I should have highlighted the difference in fit in the text.

It''s hard to judge what pictures are needed; I felt there may be too many, but they could be edited out if it was felt they were excessive. On the other hand, a step missed out might put a beginner off from attempting a task well within their capabilities, so it's not an easy judgement to make.

It's much harder to decide what level of complexity to aim for in the text. As you have done the operation yourself, it can be easy to skip over something without realising.

I enjoy writing about model engineering as much as actually making things (and it's warmer!) but just like making things, writing is a learning curve too!

Neil

Neil

Neil

I am not sure I would have described my post as constructive! but it certainly was not meant to offend. I am not in a position to criticise your skill an an author either as I have never written any articles (I am full of good intentions to write some but after realising how hard it is, keep putting it off). I do realise, more than I ever used to) that without people such as yourself our engineering magazines would just not be around.

As regards the bearing installation, angle iron is stiffer than a flat strip but only at the stiiffened edge. A large washer, even if it deformed under load would still apply the force concentrically. In general though, ballraces seem to be much more robust than we are led to believe and do tolerate loads that they are not supposed to.

Ian

Hi

I am looking forward to Issue 199 with regard to belt drive conversion to an X2 Mill Drill

As always I am interested in how others do things .

However we have to wait for the MEW in New Zealand for around six weeks delay before it is on sale

here.

Eric