I have had four 75mm under my sip saw (192 kg) for a while and notice that they seem to be misshaped with splits forming and difficult to get rolling. As they are rated at 90kg each this has been a surprise am i doing anything wrong here.
Problem with axminster rubber tyred castors
- Thread starter OLD
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johnjin
Established Member
Hi Old
I've had this problem with the rubber tyres as well. And I have got all my machinery on them and just like you they seem to go out of round. As for cracking I don't know, as I've never got on my hands and knees to have a look. In the future I will buy the solid type I think.
All the best
John
I've had this problem with the rubber tyres as well. And I have got all my machinery on them and just like you they seem to go out of round. As for cracking I don't know, as I've never got on my hands and knees to have a look. In the future I will buy the solid type I think.
All the best
John
A
Anonymous
Guest
Old
the load may not be distributed evenly across the wheels and so some may be overloaded
the load may not be distributed evenly across the wheels and so some may be overloaded
TheTiddles
Established Member
Rubber tyres are not made out of what we normally think of as rubber, ie, tree sap. In fact rubber is in almost every case plastic. Plastics are hard, even the soft ones, to make them soft you add a chemical called a plasticiser. For instance, freezer bags are made from plasticised PVC, whereas window frames are made from unplasticised PVC (hence U-PVC).
The softer you want the material the more plasticiser you add, to get really soft materials for gloves etc.. you might add 50% by weight, for tyres around 30%. This plasticiser does not bond with the molecules of plastic but instead holds them apart enough so as they can move relative to each other and hence be pliable. Given time the plasticiser leaks out (migration and leaching), leaving behind a hard plastic that cracks like you would imagine it would. To avoid this, plasticised materials need to be masticated regularly to redistribute the plasticiser around the plastic matrix, hence why car tyres on a static car perish and those on a used car do not, this is what has happened in your case probably, if you are not going to move the saw much, go for solid tyres.
Aidan
The softer you want the material the more plasticiser you add, to get really soft materials for gloves etc.. you might add 50% by weight, for tyres around 30%. This plasticiser does not bond with the molecules of plastic but instead holds them apart enough so as they can move relative to each other and hence be pliable. Given time the plasticiser leaks out (migration and leaching), leaving behind a hard plastic that cracks like you would imagine it would. To avoid this, plasticised materials need to be masticated regularly to redistribute the plasticiser around the plastic matrix, hence why car tyres on a static car perish and those on a used car do not, this is what has happened in your case probably, if you are not going to move the saw much, go for solid tyres.
Aidan
Fine Woodworking did an article some time back on various types of castor. As far as I can remember they commented that solid rubber tyres are prone to developing flat spots on relatively stationary machinery and that polyurethane is the best option.
Certainly in my case I have been very happy with these polyurethane castors from Rutlands (which seem to be identical to these ones from Woodcraft but Rutlands price is better - the Woodcraft page gives some more info on them. I have bought the castors from both sources and can't tell them apart). I have used these on my bandsaw and drill press for over a year now with no problems at all despite not moving the machines for weeks or months at a time. I guess these machines weigh about 80kg or so each, so fairly heavy but light by comparison to some machinery.
Another benefit of these castors is that when you lock them it locks both the wheel and the swivel so the machine is very stable. I use four swivelling (and locking) 3" castors on each machine - that size is plenty big enough in my case and having them all swivel makes moving the machines in a small space much easier. When I used two fixed wheels and two swivelling wheels I found myself having to slide and "lift" the machines in the confined space that I have available.
They are not cheap but I have found them to be good value. Every now and then Rutlands has sold them in packs of four swivelling castors for about £20 if I remember rightly, and despite having bought a set each time I saw them for that price I keep finding uses for more of them - strangely, they're as addictive as clamps!
Certainly in my case I have been very happy with these polyurethane castors from Rutlands (which seem to be identical to these ones from Woodcraft but Rutlands price is better - the Woodcraft page gives some more info on them. I have bought the castors from both sources and can't tell them apart). I have used these on my bandsaw and drill press for over a year now with no problems at all despite not moving the machines for weeks or months at a time. I guess these machines weigh about 80kg or so each, so fairly heavy but light by comparison to some machinery.
Another benefit of these castors is that when you lock them it locks both the wheel and the swivel so the machine is very stable. I use four swivelling (and locking) 3" castors on each machine - that size is plenty big enough in my case and having them all swivel makes moving the machines in a small space much easier. When I used two fixed wheels and two swivelling wheels I found myself having to slide and "lift" the machines in the confined space that I have available.
They are not cheap but I have found them to be good value. Every now and then Rutlands has sold them in packs of four swivelling castors for about £20 if I remember rightly, and despite having bought a set each time I saw them for that price I keep finding uses for more of them - strangely, they're as addictive as clamps!
toysandboats
Established Member
Hello Old,
I'm interested in this thread as I built a wargaming table for my son out of 3 sheets of 18mm MDF and used 8 Axminster wheels (810200 and 810201). Max load is 50kg so 8 wheels should handle 400kg and the MDF is about 150kg maximum.
Now some 10 months later, two of the tyres have "softened" and if I try to move the table, the tyres come off the metal hubs.
I think I'll go back to Axminster and see what they can offer - but thank you for prompting me to action
David Ward
I'm interested in this thread as I built a wargaming table for my son out of 3 sheets of 18mm MDF and used 8 Axminster wheels (810200 and 810201). Max load is 50kg so 8 wheels should handle 400kg and the MDF is about 150kg maximum.
Now some 10 months later, two of the tyres have "softened" and if I try to move the table, the tyres come off the metal hubs.
I think I'll go back to Axminster and see what they can offer - but thank you for prompting me to action
David Ward
From the above replies it seems that rubber tyred castors are not ideal for there purpose they do absorb small imperfections in the floor but suffer from the load they have to carry due to the chemistry of the rubber.
I think axminster (who have not offered any comments on this thread) should review there load carrying capacitys at least, as replacing them on heavy machines is a very difficult job.
I think axminster (who have not offered any comments on this thread) should review there load carrying capacitys at least, as replacing them on heavy machines is a very difficult job.
I have dug out the FWW article on castors (from March/April 2007) that I referred to above, and the following is their very brief summary of the various tyre materials:
"Steel and plastic wheels are too hard. They tend to snag on the slightest obstruction, and they can scrape or dent even the hardest of wood floors.
Rubber wheels are too soft. They have a low load capacity and their “give” can make what’s riding on them a bit tippy.
Urethane wheels are just right. They’re soft enough to climb over small obstructions, yet hard enough to keep the load stable."
They also discuss size of castor (in their view bigger is better), whether to use lockable castors or not, etc. It is an interesting article but the above bit is probably most relevant to this discussion.
"Steel and plastic wheels are too hard. They tend to snag on the slightest obstruction, and they can scrape or dent even the hardest of wood floors.
Rubber wheels are too soft. They have a low load capacity and their “give” can make what’s riding on them a bit tippy.
Urethane wheels are just right. They’re soft enough to climb over small obstructions, yet hard enough to keep the load stable."
They also discuss size of castor (in their view bigger is better), whether to use lockable castors or not, etc. It is an interesting article but the above bit is probably most relevant to this discussion.
toysandboats
Established Member
I spoke to Axminster today and Technical Support stated that the rubber wheels are intended to be used regularly i.e. on a saw that is wheeled about daily. They are not meant to be left stationary for 3 months as I did.
I have now ordered 8 of the hard plastic ones (600768) and they did give me 10% discount even though the deforming wheels were 13 months old. They also paid the P&P.
Thanks to Axminster for the goodwill gesture.
David Ward
I have now ordered 8 of the hard plastic ones (600768) and they did give me 10% discount even though the deforming wheels were 13 months old. They also paid the P&P.
Thanks to Axminster for the goodwill gesture.
David Ward
