Tape belt measuring - UK Vintage Radio Repair and Restoration Discussion Forum

CHRIS_F · 27th Sep 2019, 11:06 am

Hi All

Would this be a valid way to measure belts? See first image. Would that belt be a 75mm belt? Also when a belt is fitted how do you know if it’s too tight or too loose? I have no old belts for reference and tried a bit of string to get approximate sizes, When fitted how far should it deflect sideways with a slight pressure applied or is there a better way to judge how it fits?

The belts I’m currently looking for are for my kids Hitachi TRK 510er’s does anyone happen to know the size, I’m guessing around 70mm and 56-58mm for the small one I don’t have any in that size and 54mm seems a bit tight to me.

Thanks guys,

TIMTAPE · 28th Sep 2019, 2:50 am

The belts I buy from my Australia supplier are described by inside diameter. A US site lists by inside circumference.

Without a reference it's hard to gauge size exactly. I guess it's always a tradeoff between tight enough for reliable non slip drive but not so tight as to unduly strain bearings, and the belt itself.

crackle · 28th Sep 2019, 7:03 am

Very expensive but they are available on Ebay
https://www.ebay.co.uk/itm/Belts-Rie...i:133182549317

paulsherwin · 28th Sep 2019, 9:43 am

Buy one of the cheap generic belt sets from eBay and find the best match by trial and error.

Example: https://www.ebay.co.uk/itm/50PCS-Uni...e/372738596645

stevehertz · 28th Sep 2019, 10:14 am

If a replacement belt is not the exact size, ie a true manufacturers' replacement belt, then my own personal opinion is for it to be slightly on the tight side. 1) it's unlikely to hurt the bearings, 2) belts stretch and go looser in time anyway. When you've experimented with belts and see the range of sizes that will actually 'work', it's not that critical.

27th Sep 2019, 11:06 am	#1
CHRIS_F Tetrode Join Date: Apr 2014 Location: Merseyside, UK. Posts: 57	Tape belt measuring Hi All Would this be a valid way to measure belts? See first image. Would that belt be a 75mm belt? Also when a belt is fitted how do you know if it’s too tight or too loose? I have no old belts for reference and tried a bit of string to get approximate sizes, When fitted how far should it deflect sideways with a slight pressure applied or is there a better way to judge how it fits? The belts I’m currently looking for are for my kids Hitachi TRK 510er’s does anyone happen to know the size, I’m guessing around 70mm and 56-58mm for the small one I don’t have any in that size and 54mm seems a bit tight to me. Thanks guys, Attached Thumbnails

28th Sep 2019, 2:50 am	#2
TIMTAPE Octode Join Date: Jul 2006 Location: Perth, Western Australia Posts: 1,969	Re: Tape belt measuring The belts I buy from my Australia supplier are described by inside diameter. A US site lists by inside circumference. Without a reference it's hard to gauge size exactly. I guess it's always a tradeoff between tight enough for reliable non slip drive but not so tight as to unduly strain bearings, and the belt itself.

28th Sep 2019, 7:03 am	#3
crackle Rest in Peace Join Date: Mar 2011 Location: Basildon, Essex, UK. Posts: 4,100	Re: Tape belt measuring Very expensive but they are available on Ebay https://www.ebay.co.uk/itm/Belts-Rie...i:133182549317

28th Sep 2019, 9:43 am	#4
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,947	Re: Tape belt measuring Buy one of the cheap generic belt sets from eBay and find the best match by trial and error. Example: https://www.ebay.co.uk/itm/50PCS-Uni...e/372738596645

28th Sep 2019, 10:14 am	#5
stevehertz Dekatron Join Date: Sep 2011 Location: Rugeley, Staffordshire, UK. Posts: 8,831	Re: Tape belt measuring If a replacement belt is not the exact size, ie a true manufacturers' replacement belt, then my own personal opinion is for it to be slightly on the tight side. 1) it's unlikely to hurt the bearings, 2) belts stretch and go looser in time anyway. When you've experimented with belts and see the range of sizes that will actually 'work', it's not that critical. __________________ A digital radio is the latest thing, but a vintage wireless is forever..