Thank you Paul for the technical input. I also appreciate the prompt response from your team. It would be great to see the bearing spec ratings on the VexPro website, similar to how other suppliers provide a rating and similar to how you provide full disclosure on your other products (ie 775Pro).
This gives us confidence this year to continue using the product without modification to our design. We just started using thunder hex this year for intake rollers, drive train and shooter. The high RPM application was our only concern.
You mentioned getting the fit right is important when you turn down hex stock to use thunder hex bearings (13.775mm round). When using the thunder hex stock are there any tips and tricks to get the right diametrical clearance, understanding the oversizing from the manufacturer? When working on the lathe and a 3 jaw chuck we had to try a few times and experiment to get the fit a âslight press fitâ. As soon as the tool started removing material from the part was too much to get a press fit. We also tried a live center to keep it straight. It took a couple times and some scrap material to finally get it right. When we were able to turn down the shaft to achieve the correct fit the cuts were still inconsistent. This may have to do with the lack of eccentricity of the part vice thunder hex stock, Iâm not sure how to get it perfect. It is unfortunate that the thunder hex stock still requires precision machining to get the âslight press fitâ. This burned a lot of our manufacturing time this year.
Is this something VexPro is looking to change in the future?
Did you try using some emery cloth instead of a cutting tool to take off the necessary material?
Weâve done that for all of our thunderhex this year and it just takes a few seconds. You could even chuck the thunderhex in a drill press, mill or hand drill and take off the necessary material with emery cloth, no lathe required.
This. Since you are only taking off a couple 0.0001âs of an inch you wonât be able to hold that tolerance cutting unless you have a really nice lathe. We sand the thunderhex stock on the lathe with emory cloth until the axle turns a certain shade of silver and get very consistent results.
Have not tried Emory cloth to get the shaft to the right diameter. Seems like that might work better. Will give that a shot for the next few. The drive axles are made from steel hex so our only real option was to use a lathe and cutting tool to get the 13.75mm.
The Emory cloth is absolutely the way to go. Basically, we take off the anodizing on the round part of the thunderhex and it is a nice slip fit.
However, right now since the thunderhex is slightly oversized it is the perfect size for a press fit. We use our small arbor press to get the shaft in the bearings.
With that said, the Thunderhex used with thunderhex bearings is supposed to be a nice slip fit. The bearings are completely within our expected tolerance but the thunderhex stock is a few 10 thousandths large. This is large enough to make it a slight press fit. It is so close that when it is about 30-35 degrees here in Texas the shafts are a slip fit!
In any case, once we run out of the current inventory we will make sure the next batch is within our size requirements at 75deg F.
