Hi, Recently my pulley & bearing assembly for truing tyres fitted to wheels with 3 mm axle went missing.
Faced with buying another pulley from a dealer at $38 each I decided to make my own
Mandrill For a lot less I ended y=up with a Mandril ready to go at any time to true up tyres mounted on 3 mm rims.
Parts were a 3 mm axle 70 mm long or so. A MJK lightweight 3/32 axle x 13mm rim (17” ). 2 x MJK acetal ( plastic ) 3/32 “ Scalex Type axle bearings . 2 x BRM 3 mm axle stops .
I drilled out the wheel & the Acetal bushes in my metal lathe to fit the 3 mm axle . The picture shows how the mandril is assembled & also fitted to the Area Tyre true.
The same mandril will be done for 3/32 & 1/8’ axles .
I fitted the second grub screw to the MJK rim to give a better grip on the axle .
The grub screw in the Area pulley ( red anodised one ) has been stripped fairly easily by various people of different strength using it . I had to try and drill & tap another grub screw hole
to get over the problem . It is not easy to get the correct position for a second grub screw hole. Hence I have bought a couple of the original pulleys .
The last one I bought was stripped in 2 weeks of use - so therefore the ban on other people than myself using the equipment. For other reasons the ban will still apply even with the new mandril idea . However having the Mandril permanently set up using the MJK wheel should eliminate the stripping grub screw problem and be a help in speeding up the tyre truing process. .
For those who have made the very wise investment in buying their own Tyre Truer I am happy to help making up permanent mandrils for them to help save having to buy new pulleys. They can be saved for using on front axles where the plastic wheels cannot be removed.
As I have suggested I am able to true others tyres but with prior arrangement and away from the start of race meetings
Here is the mandril for 3 mm axles . The red on the MJK wheel is where the rubber ‘O “ ring drive belt runs .