Steve, apologies for not replying sooner.

I also need to make pulleys for mine too which came with the only the ‘C’ on the motor shaft. The diameters for this are 27.5mm on the upper sheave and 19.8 on the lower. (Thats a little odd… have I got that around the wrong way? I will check.)**

Can you let me know the diameters of your motor’s ‘B’ sheave are please?

From the speeds plate on my machine and those ‘C’ pulley dimensions above, I calculate (it’s the 18k RPM max version by the way, …some machines are only 9 or 12k from what I seen on the web)   ‘A’ pulley = top 155.6mm, bott. 81mm, ‘B’ pulley = top78mm bott 40.4mm.  These are based on a motor speed of 3180 RPM at a voltage of 420V. These don’t quite match with the pics from the Parts manual though.

I haven’t been able to locate an Operators Manual for the Herbert ‘B’, only the spares book from which I included pics of the relevant pages in the earlier thread. But if we found one, I’m quite sure it would say “relube through the two nipples on the front of the spindle housing about once per year with 1/2 and ounce of Shell Alvania R3 or equivalent”.

The danger is that for something that has to run at 18k this greasing policy is only safe for very intermittent duty due to heat generation. To avoid this, I rebuilt both the spindle and the spindle drive with non-contacting enclosed bearings. These have high speed capable greases and should out-last me without any further relubrication.

The two nipples by the way, each go into a hole in the spindle unit and a hole in the spindle drive unit. When I stripped mine, both parts were chock-a-block with grease, and excess was leaking out of the bottom making things very messy indeed. This is the one part of this machine’s design that wasn’t very well thought-out, in my humble opinion.

Gerry

** actually it must be the correct way up because this is the only way the ‘C’ marking is visible.

I am also rebuilding a B type. The spindle pulley remains the same. Depending on the exact motor speed under load (nominal 2ole 3000rpm) Then I calculated that the high speed pulley was 12 cm diameter, the medium one is 6 cm and the low speed was 3 cm.

So the high speed pulley has two identical diameters as does the medium speed one. The low speed could do with a 3cm diameter and for the very lowest speed 2.8 cm to give the plate rated speeds.

I don’t have any of the 3 motor pullies, so would be interested in knowing if they are steel? I know that Gerry is intending to make them from aluminium. I have a much earlier and far more massive Herbert high speed drill. The motor pullies on this are aluminium.

As for lubrication, Gerry is the man that knows his bearings, just follow his advice.

Andrew.

Oh dear, now I’m totally confused. Perhaps I’m missing something?

Firstly motor speed. I think Andrew is right to use 3000. Under a significant load the speed will come down from synchronous but I have just measured mine and with a belt on its doing 2965. Perhaps on high ratio that will come down further but I would expect Herberts would keep it simple.

My speed plate is shown here:

As we know the motor speed, to get the above speeds we can convert this to a ‘ratios table’ as below:-

6          3         1.5

4.33    2.17         1

To convert this into diameters of the MOTOR pulley I then multiplied all of the above ratios by the diameters that I actually have on the fixed SPINDLE pulley. (These are 27.5mm on the upper sheave, 19.9mm on the lower, on my machine) This gives me MOTOR pulley diameters of:

A             B              C

165mm    82.8mm    41.2mm

85mm      43mm      19.8mm

My two stepped ‘C’ spindle pulley is actually 39mm (upper sheave) and 18.6mm (lower sheave). The differences from the calculated diameters are about 6%. This may explained by wear of the crown and/or assuming a nominal 3000RPM motor speed.

I note that the MOTOR pulleys in the schematic above are not stepped but I thought this would be simply artistic license. However in the parts pictures, only a slight step is shown as you can see here:

So where have I gone wrong chaps ?

Gerry