# roughing end mill actual vs nominal



## PeterT (Apr 2, 2018)

I discovered something as I was making a rather intricate part the other day. Thankfully I did not botch it, but it was skinny close. Turns out a 1/4" (=0.250") diameter fine tooth roughing end mill (happens to be Accusize brand) measures 0.255-0.256" in actual diameter. I was doing work on a rotary table where I was offsetting by a radius using DRO. I gave myself what  thought was a healthy allowance to clean up to final dimension with a regular end mill after the rougher. Only to discover the regular end mill was cutting air because it was 'on spec' at  0.250" +/- 0.001"  I haven't gone back to check my other rougher EM's but might explain a few past mysteries I had chocked up to setup. 

Anyone else experience this diameter discrepancy with brand name roughing end mills? I just naively assumed they would be pretty close to reference size.


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## Tom O (Apr 3, 2018)

You would think that they would be close, I have noticed that they can be a couple thou over though. Mine has the probe and tool measuring on it I'll have to get a roughing end mill and try it.


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## Alexander (Apr 5, 2018)

At my day job I handle hundreds of  brand name endmills every month. All of them from Kanametal, Sandvik,  Harvey tool and Widia. I have never seen one oversize but often they come in as much as -.001". These company's listed have good quality control and wouldn't let tooling leave the factory without being checked. Accusize is a company that does most of its business online because the quality isn't good enough for manufacturing community to endorse. That being said I have a few accusize tools in my garage but I'm just a hobbyist when I'm experimenting at home.


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## PeterT (Apr 5, 2018)

I got a similar response on another forum. Basically if it doesn't have a ANSI/ISO/whatever rating that prescribes tolerance (which they don't), then basically it can be anything. They cut reasonably well & price wasn't too bad. So the moral of the story is: don't assume, measure the cutter OD!


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## Alexander (Apr 5, 2018)

I manufacture parts to ISO 9001:2015 standards and I can say the ISO program is very thorough and the organisation has allot to offer companys that get certified. If you see a tooling company that has current ISO certification  you can expect a higher level of quality and consistency for sure.


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## PeterT (Apr 5, 2018)

I just had to go back & check. They say ISO 9002. Hmmm.... Gunna call BS on that. Maybe they mean 'made in an ISO facility', or 'intended for the ISO Olympic team, but didn't make the cut', or... etc. etc.


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## Alexander (Apr 5, 2018)

I believe there is an easy way to check with iso about there status in the iso program.


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## Alexander (Apr 5, 2018)

If they are I would think you could email a complaint and at least get a free replacement tool


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## Tom Kitta (Apr 20, 2018)

Accusize from my understanding is a hobby grade company similar in tooling quality to say Busy Bee / KMS. I have some of their stuff and its good - you just have to realise that not all of it is good or good enough for say what Alexander is doing. 

I source almost all of my tooling of eBay (that can be shipped) and thus when it is a new tool its quality is superb and price is lower than Accusize. I mean what would you rather use Accusize or Niagara cutter with former being cheaper?


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