First time reaming question

[stupoty]

Off size metrics seem to be a thing , just harder to find

8.1mm Left Hand Spiral Flute HSS 5 Percent Cobalt NC Machine Reamer - K21B1 (YG-1)

The YG-1 K21B1 series Reamer has a HSS 5 Percent Cobalt substrate with sizes ranging from 2-20mm diameter. These come with whole number shanks making them ideal for clamping within hydraulic chucks and ideal for machining Steel, Stainless Steel, Cast Iron and Non-Ferrous materials.

www.cutwel.co.uk

Stu

 

[WobblyHand]

Or polish the shaft to the fit you require within a tenth.

Done that too. Pain in the neck to get it ok. As a beginner with less experience, choosing appropriate grits and dealing with unexpected work holding requirements for a small finished parts, it's not easy. Probably simple, if experienced.

Honestly, can't imagine not using over and under reamers. Great for the emergency I previously mentioned, and for mundane things like interference pin fits.

As an example, try polishing a pin that's about 2mm in diameter, for 4mm of it's 8mm total length. Maybe you can do it with ease. Not me.

 

[RaisedByWolves]

They are great for "rescue" efforts, like when you find out your stock is 0.2505" diameter, to your surprise, and you already reamed the hole 0.2500". So grab the 0.2510" reamer, and life is good again . Ask me how I know...

Well use a fit like that (.0005 under) to retain a dowel pin to a part.

Certain die sections we have need to be taken out from the top of the die while hanging and this a good way to keep the dowel in place for locating it when it goes back in. Plus any wear is then in the sub section and not the die shoe.

Subsections are easy to fix and work on, die shoes, not so much.

 

[mmcmdl]

Add to the above , prototype molds . Many of our molds had to be resized when allowing for shrinkage of whatever material was selected for production. Over-under for the dowel pins for split and multi sectional cavities were used before the final molds were made .

 

[Janderso]

Reamers are tapered .0005 per inch so only the front lead is doing any work .

I didn't know that