• Guest, Help us understand what we can do better in future. Click Here!

What size screw is this?

#1
I need to replace two screws on my bandsaw. I'm assuming metric.. maybe. The threaded portion measures 0.234" (6mm?) OD and looks to be 20 TPI according to my SAE thread gauge. I started looking through online screw charts but got dizzy real fast. Is there an online screw calculator that would solve this mystery in a less pain full fashion?

Thanks
 

John Conroy

Well-Known Member
Premium Member
#2
Most of the screws on my Taiwanese bandsaw are sae thread. It's probably 1/4" 20 tpi. 20 tpi is almost exactly metric 1.5mm thread pitch but m6 X 1.5 is pretty rare, the common thread,pitch for m6 is 1.0.
 

PeterT

Ultra Member
Premium Member
#3
Not sure about where your bandsaw originates from but its unfortunately quite common to have a mish-mash of imperial & metric fasteners on machines these days of Asian origin or outsourcing. The OD isn't a great indicator because often times the fastener isn't well made. Or as John says there are certain combos that are quite close to one another & if you assume wrong then its possible to bugger up the threads. If you don't already have a screw pitch gauge, they are a good investment.

There are many thread tools on the net but I use this one a lot. It shows the tolerances & comes in handy when designing & cutting threads particularly.
http://theoreticalmachinist.com/Threads_UnifiedImperial.aspx
 

Attachments

#4
I have a selection of SAE and metric nuts at the shop. I just try the nut on the mystery bolt until I find one that threads on nicely

Or I’ve used a thread chaser to do the same thing, especially if it’s metric