Spur gear help.

I am in need of some help in working out which type of spur gear i need. ive trawled the internet for some basic info on spur gears but it rapidly gets very technical and gets its very frustrating with all the different types there are.

My Milling table has a small gear box which uses spur gears to drive the gear box -

the ratios are

34/14 = 1/2" per min

29/19 = 3/4" per min

24/24 = 1 1/4" per min

19/29 = 1 7/8" per min

14/34 = 3' per min

I only have the 34/14 ratio so i'm looking to get the 29, 24 (x2) and a 19 toothed spur gears.

The centre between the spindles is 61mm (2.375" - 2 3/8ths) approx.

Can some one please advise which type of spur gear I will need and what are the crucial dimensions I should be looking for.

Can you give a more accurate ctr distance as you are on the border line between 10DP and MOD2.5

60mm (2.362" ) would work out OK with MOD 2.5

2.400" (60.91mm) would work out OK with 10DP

Edited By JasonB on 15/01/2021 17:14:20

Accurately measure the OD of the 34 tooth gear and tell us the make and model of milling machine.

Andrew

I looked at the 'Rushgears.com' calculator & as Jason says 1.375" centre distance doesn't give a meaningful answer. I'm guessing the mill is a 'Herbert'?

Tony

Edited By Tony Pratt 1 on 15/01/2021 17:18:36

Yes it is the Herbert Mill - One of the gears does have 10DP stamped on it - Is this the "type" I need to be searching for

I have looked at mod 2.5 and they seem to have more ratios.

Can anyone suggest a supplier ?

Those are 10DP gears, but you don't have to use 10DP, you could use 20DP (myford) gears and double the tooth count, or any other DP that will achieve the 2.40" centre distance.

Just as an illustration, HPC Gears price for 10 DP is £23.42, £28.13 and £32.78 for 19t, 24t and 29t.

eBay prices for 20DP Myford gears are £10.50, £18.95 and £26.40 for 38t, 48t and 58t. The 58t seems to be less common.

A further option may be to use timing pulleys and a toothed belt if you can find a more economic source of supply than traditional spur gears.