Thread: Reamers 101

Reamers need to be started (and run) square to the job. Doing this by hand is difficult and can lead to bell mouthing, chatter and misalignment. Pilots are used to minimise these issues. When ever possible I use my adjustable reamers with pilots as it make the job a lot easier. As an added bonus, if you are reaming to align two holes across a bracket of some sort a pilot will help keep them concentric too.

Michael

Originally Posted by azzrock

hi every one. I have some large adjustable types . Im a bit confused some have a pilot. but the others dont.
whats the difference? if they where here id just have a look.
aaron

The type of adjustable reamers with loose blades and a large adjustment range is impossible to hold square by hand. They need to be guided in a drill press (you still turn them by hand) or tapping stand or by the tailstock in a lathe. The pilot extension is needed when you must use them completely freehand, and still expect a halfway accurate result.

Fixed hand reamers have a long taper point and can be used by hand without guide (unless it is used for a hole into thin plate). Expandable reamers have by their very design an integrated pilot.

Speaking of reamers, yesterday I used two of my adjustable hand reamers.

One to make a neat fit to an in shed made 19mm pulley hole. The pulley was nearly 40 mm thick so this took a while but it came out sweet. The second was a 22.2mm hole in a clamping piece to hold a piece of bicycle seat stem (not on a bike). Being a static clamp this didn't need to be as accurate as pulley but I only have 1/2 mm drill step sizes around the 22 mm mark and didn't want to go as large as 22.5 so I went drilled to 22 and then reamed the rest. Guess what my poring bar starts at - yep 23 mm - I should make a smaller one for jobs like this. It wasn't needed for the the second piece but I need to make an conical socket type holder to hold the reamers vertically in the DP.

At the end of the day I went to check the mail box and found my 26 - 29.5 and 29.5 - 33.5 reamers have arrived from CTC. I'm going to use these to make a couple of 28 and 32 mm hole pulleys.

Thanks All,

Great thread with lots of useful info.