1.5 pitch belts?

This topic has 11 replies, 4 voices, and was last updated 30 January 2026 at 10:35 by andy198712.

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18 January 2026 at 12:48 #833053
andy198712
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@andy198712
Hi,

looking for some guidance. I need a longer belt for my sieg lathe.
the stock belt says 1.5×100

now I take this to mean 1.5mm pitch and 100 teeth?

belt is 9.5mm wide.

length is circa 470mm

i need a belt 510mm which I make out to be about 107 teeth at this pitch if my maths is right plus or minus two?!

I can’t find many of these… is there a more common name to search I don’t know about?

thanks
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18 January 2026 at 13:38 #833057
JasonB
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@jasonb
No the pitch is 1.5 x pi so 4.713mm pitch. which works out about 108T but you will be hard pushe dto find one that is not standard for that or other similar machines
18 January 2026 at 13:47 #833058
andy198712
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@andy198712
Ah! And I always cheated at maths …. 😂

yeah I’ve found one potential on AliExpress and thats it, they all seem to stop at about 100 teeth.

Thinking about it I’ll probably make some other pulleys either Vee or poly vee long term if there easier to get hold of but till then… just need something.
18 January 2026 at 13:50 #833060
andy198712
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@andy198712
Or I just do the pulleys now…. And get either different pitch or design…
18 January 2026 at 14:20 #833061
peak4
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@peak4
If I read this correctly the 1.5 refers to the belt height, and 100, the tooth count.
This advert for a Seig belt might shed more light; or it might further confuse.
https://www.ebay.co.uk/itm/176634042764

“Synchronous lathe Belt GT2 M1.5 100T 9.5mm SIEG SC2-019 JET BD-X7 Grizzly G0765”

Which claims a GT2 belt, used on 3D printers etc.
That said, when I look up GT2 belts, the 100 tooth count doesn’t seem correct for a 475mm belt, so maybe there are using an erroneous description

Axminster lists your current belt (maybe)
https://www.axminstertools.com/drive-belt-for-sieg-sc2-lathe-timing-1-5-x-100-burt002348

Bill
18 January 2026 at 14:40 #833065
not done it yet
Participant
@notdoneityet
I have only once bought a belt via epay. That was for my Bodge planer. Apart from that, I have always gone to my local belt/bearing supplier, taking along my belt/bearing and see what they have. Mostly agricultural sizes are what I have usually dealt with!

These may be smaller than they stock, but it is a suggestion. Longer belts can be tensioned by either moving the motor or adding an idler.

Good luck with your search.
18 January 2026 at 15:09 #833071
JasonB
Moderator
@jasonb
On 18 January 2026 at 14:20 peak4 Said:

If I read this correctly the 1.5 refers to the belt height, and 100, the tooth count.
This advert for a Seig belt might shed more light; or it might further confuse.
https://www.ebay.co.uk/itm/176634042764

“Synchronous lathe Belt GT2 M1.5 100T 9.5mm SIEG SC2-019 JET BD-X7 Grizzly G0765”

Which claims a GT2 belt, used on 3D printers etc.
That said, when I look up GT2 belts, the 100 tooth count doesn’t seem correct for a 475mm belt, so maybe there are using an erroneous description

Axminster lists your current belt (maybe)
https://www.axminstertools.com/drive-belt-for-sieg-sc2-lathe-timing-1-5-x-100-burt002348

GT2 belts are much too fine. As I said the pitch is 1.5 x pi not the 2mm of a GT2 belt and nothing to do with height. and where did 475mm length come from

Do the maths, the existing belt is c470mm for 100T so 470/100 = 4.7 therefore you want a pitch 4.7. They are the same principle as Module gears, the circular pitch of a 1.5Mod gear is 4.71mm

Also be aware that Sieg did not use this type of belt in recent years so a SC2 may take a different belt than the older C2. Same with my X3 which is an early model and uses these 1.5 belts, newer ones don’t.

If you need something just to get out of trouble and make a replacement pulley then possibly a 5mm pitch 102T belt at 10mm wide may just do as that would be 510mm long. https://www.ebay.co.uk/itm/156233189203
18 January 2026 at 15:31 #833072
andy198712
Participant
@andy198712
Megadyne ISORAN RPP 500 RPP5 9mm

tempted to give these people a ring but they have a handy how to measure your belt tab

the mention measuring ID of the belt… and I’ll measure the pitch mainly later, centre of one tooth to the centre of next to check.

oddly not as straight forward as i thought it would be!
18 January 2026 at 15:58 #833074
JasonB
Moderator
@jasonb
Details of 1.5 Mod belts, pitch as I said I said.
18 January 2026 at 16:37 #833079
JasonB
Moderator
@jasonb
105 and 110T are available in the 1.5Mod which come out a bit longer or bit shorter than your 510mm might do the job.
18 January 2026 at 18:13 #833086
andy198712
Participant
@andy198712
Thanks Jason! Yeah that’s the one supplier I could find! I’ve ordered those to see if they’ll work for me 🙂
30 January 2026 at 10:35 #834931
andy198712
Participant
@andy198712
the belts look to be a perfect fit!

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