Charlie_6ft Posted January 22, 2020 Report Share Posted January 22, 2020 Hi, I am eyeing off an old bandsaw (I think it's about 32") and have thrown a few queries to Matty (L.S. Barker1970) but thought I would stop pestering him and share my questions here in the event it may help others. The saw is about 350klms from me so to daylte I have relied on pictures and a multitude of questions to the owner. Q1. From the pics I have been provided it looks like at the very least it'll need new vulcanized rubber on the idler and drive wheel. Through a query a year or two ago someone mentioned a place in Goodna (Brisbane) that charged about $250, but can't find the info anywhere. Does anyone know where I may be able to get the wheels re-done in Brisbane? Q2. I am told it was working fine last time it was used but has just been sitting in a shed for a while (it belonged to an ex-boat builder). With that said, I may need to repour the babbitt bearings, I did a quick Google and there doesn't seem to be a shortage of people in Australia who can supply the lead based babbitt metal. But who in Brisbane could someone recommend? Q3. The motor on the saw is a Crompton Parkinson 2.75HP Three Phase motor. On the motor plate it has 940RPM. This sounds pretty slow? I would be replacing the motor with a Single Phase 3HP motor (Cheaper than a VFD) which looks very straight forward given the foot mounting assembly. What RPM would I seek in a motor as a replacement? I have read anything from 1400RPM to over 3000RPM! Quote Link to comment Share on other sites More sharing options...
wtnhighlander Posted January 22, 2020 Report Share Posted January 22, 2020 A 940 rpm motor would yield around 1500 inches per second blade speed over 32" wheels, with no reduction. I'm sure there are pulleys involved, you will need that ratio to determine the appropriate motor rpm. Is the power grid in your part of the world 50hz? If so, that 940 rpm rating will likely be listed as 1000 rpm on a modern motor. It used to be common to see full load speed ratings, now I see no-load ratings more than not. Regarding the wheels, would modern tires like these work? I'm not familiar with that saw, but most folks seem to prefer urathane these days. Soak them in hot water and they will stretch over the wheels without too much effort. Quote Link to comment Share on other sites More sharing options...
Chip Sawdust Posted January 22, 2020 Report Share Posted January 22, 2020 I'm not much help, but dang that sounds like an awesome bandsaw! Quote Link to comment Share on other sites More sharing options...
Charlie_6ft Posted January 22, 2020 Author Report Share Posted January 22, 2020 Thanks chaps, Q1. I found the people today I was looking for regarding vulcanized rubber services. They are called Queensland Rollers & Liners (Cobalt Street, Carole Park QLD) over near my part of the world and advised me that it would cost between AUD$265 - AUD$300 ex GST. There are blue or orange polyurathan options but think from America which with postage may end up nudging the price up. Q2. Babbit bearings - It may not be required BUT will find out in about 3 weeks when I pickup the saw. Q3. I think it may have had a conversion at some point regarding the pulley (see pics) and is driven by 2 x V-belts. I've got the choice out of 4 Pole (1400rpm) or 2 Pole (2800rpm) both 50Hz for a Single Phase motor. OR I get a VFD and I make use of it being variable speed and can add in soft start, etc. BUT regardless I'll get all the figures and then run it through an RPM calculator to figure out the speed. 1 Quote Link to comment Share on other sites More sharing options...
wtnhighlander Posted January 22, 2020 Report Share Posted January 22, 2020 I would go with the 2 pole motor, unless you plan to change the pulleys, too. Doubling the speed will increase heat build-up from friction. It will certainly work, but require modified cutting practice to get the desired results. Quote Link to comment Share on other sites More sharing options...
Tom King Posted January 22, 2020 Report Share Posted January 22, 2020 I like having a VFD on my big bandsaw. Listening to the slow windup to speed is worth it, alone. I can also run it under, or over normal speed. We ran it 10% over, for three or four hours at the time, and nothing got even warm to the touch. Babbit bearings are the smoothest running bearings in existence, until they need to be repoured. I've never owned any, but have had my hands on such machines running. With no personal experience, I have no idea how long they last. Quote Link to comment Share on other sites More sharing options...
Charlie_6ft Posted January 23, 2020 Author Report Share Posted January 23, 2020 19 hours ago, Tom King said: I like having a VFD on my big bandsaw. Listening to the slow windup to speed is worth it, alone. I can also run it under, or over normal speed. We ran it 10% over, for three or four hours at the time, and nothing got even warm to the touch. Babbit bearings are the smoothest running bearings in existence, until they need to be repoured. I've never owned any, but have had my hands on such machines running. With no personal experience, I have no idea how long they last. Hmm ... perhaps I re-visit this idea. A VFD is about $50 more expensive than a motor replacement BUT am keen on gentle startup. Is it purely just to variables you need to set: KW Full load current Quote Link to comment Share on other sites More sharing options...
wtnhighlander Posted January 23, 2020 Report Share Posted January 23, 2020 The VFD will want to know the "normal" speed of the motor you pair it with. Even though the drive varies speed by changing the frequency, it will likely have a display scaled to RPM or % of nominal speed, so it needs a known point to scale from. Quote Link to comment Share on other sites More sharing options...
Tom King Posted January 23, 2020 Report Share Posted January 23, 2020 The VFD's I have will do many more things than I have even learned how to do with them. I'd have that old motor checked out first. If you need to replace the motor, it probably wouldn't make sense to buy both a new 3-phase motor, and a VFD. Quote Link to comment Share on other sites More sharing options...
riqmar Posted January 24, 2020 Report Share Posted January 24, 2020 Regarding the babbit bearings: as newly poured bearings, there typical are removable shims between the upper and lower halves of the bearing. These shims can be changed to thinner or thicker ones, or be removed or replaced with fewer or different ones, or to a lesser extent the fit can be adjusted by the degree to which the bolts are tightened. If it comes to repouring, it is not all that difficult. Regarding the motor: is a phase-convertor a viable option? Can you simply change a pulley or two to achieve the desired speed? Regarding the tires: if the wheels themselves are not crowned then the tires must be crowned after mounting. Good luck; it is well worth the effort. Quote Link to comment Share on other sites More sharing options...
Popular Post Coop Posted January 25, 2020 Popular Post Report Share Posted January 25, 2020 I’m often amazed and impressed at the Woodworking and non-woodworking knowledge the members on here have. And just as often have no clue as to what they are saying on most subjects but sounds cool anyway! 4 Quote Link to comment Share on other sites More sharing options...
Spanky Posted January 25, 2020 Report Share Posted January 25, 2020 Don’t tell me the Houston Boy sat in the back of the class room at school. 1 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.