Reamers

MattF · Mar 30, 2021

Anyone ever used any generic, import reamers? Just wondering if they're usually made to a decent tolerance, or whether they're generally naff.

Brad93 · Mar 30, 2021

Don’t know but I’d love to know if it’s cost effective having old ones sharpened compared to buying new.

Kram · Mar 30, 2021

Yes I have two sets from amazon, they were £5 for a 3-12mm H7 set and £7 for a 3-10mm H8 set which I havent used yet.

H7 is generally +0.2mm, so clearance holes.
H8 is close fit.

The h7 holes measure good with the ball gauges, in my opinion. Wouldnt want to rely on them for anything safety critical but remember its a £5 set rather than £15+ each that the branded ones cost. Ive got a few branded ones, they cost £10 each used.

Pilgrim22 · Mar 30, 2021

Kram said:
Yes I have two sets from amazon, they were £5 for a 3-12mm H7 set and £7 for a 3-10mm H8 set which I havent used yet.

H7 is generally +0.2mm, so clearance holes.
H8 is close fit.

The h7 holes measure good with the ball gauges, in my opinion. Wouldnt want to rely on them for anything safety critical but remember its a £5 set rather than £15+ each that the branded ones cost. Ive got a few branded ones, they cost £10 each used.

Have you got a link to them on amazon please?

Kram · Mar 30, 2021

Heres the links, not available from the same seller and tbe second price has gone up. It took quite a bit of searching to find the H8 set.
www.amazon.co.uk/gp/aw/d/B07V4747BW
www.amazon.co.uk/gp/aw/d/B07VWVH8XL

MattF · Mar 30, 2021

Kram said:
Yes I have two sets from amazon, they were £5 for a 3-12mm H7 set and £7 for a 3-10mm H8 set which I havent used yet.

H7 is generally +0.2mm, so clearance holes.
H8 is close fit.

The h7 holes measure good with the ball gauges, in my opinion. Wouldnt want to rely on them for anything safety critical but remember its a £5 set rather than £15+ each that the branded ones cost. Ive got a few branded ones, they cost £10 each used.

Which would be preferred for reaming out a bronze bush for a rotating shaft; H7 or H8?

Brad93 · Mar 30, 2021

MattF said:
Which would be preferred for reaming out a bronze bush for a rotating shaft; H7 or H8?

H8

Brad93 · Mar 30, 2021

See chart

Brad93 · Mar 30, 2021

I suppose really you need to measure your shaft :whistle:

and see what the tolerance is.

it it Oilite or Phosphor Bronze. Oil or grease lubrication?

MattF · Mar 30, 2021

Brad93 said:
I suppose really you need to measure your shaft and see what the tolerance is.

it it Oilite or Phosphor Bronze. Oil or grease lubrication?

Oil lube. Not got the shaft here as yet.

Kram · Mar 30, 2021

I dont claim to understand the ISO fits system, but most of them seem wrong (not your chart, the system!), example being force fits, why would you have a +0.2mm hole for a force fit as it means you need a +0.25mm shaft. Please can someone explain it with an example or two.

MattF · Mar 30, 2021

I didn't even know there was a 7 or 8 until you mentioned it, so you have company in the clueless camp.

addjunkie · Mar 31, 2021

Kram said:
I dont claim to understand the ISO fits system, but most of them seem wrong (not your chart, the system!), example being force fits, why would you have a +0.2mm hole for a force fit as it means you need a +0.25mm shaft. Please can someone explain it with an example or two.

It only works if you make both pieces to the correct tolerences. Its in the zeus book. So the fit would be something like H7G6 denoting two parts.

Hole And Shaft Basis Limits and Fits,Hole Limits And Fits,Hole And Shaft,Tolerance,

Hole And Shaft Basis Limits and Fits,Limits and Holes,hole,limits,fit,Iso Tolerance,ISO tolerance system, Free Running,Loose Running,Sliding,Easy Runing, Locational Clerance, Locatinal Transition,Force Fit, Medium Runing,Engineering,Coban Engineering,

www.cobanengineering.com

Agroshield · Mar 31, 2021

addjunkie said:
...the fit would be something like H7G6 denoting two parts.

It is also a system where you have to be very, very careful when writing things down. It also makes oral communication difficult. The capitalisation or not (upper or lower case) is very important. H7G6 does not exist. H7g6 does exist.

Munkul · Mar 31, 2021

That Coban chart is really confusing.

$fractory.com$

Limits & Fits | Types of Fits Explained & Tolerance Charts | Fractory

Limits and fits are a set of rules regarding the measurements and tolerances of mating machine parts to achieve the best working conditions.

$fractory.com$ fractory.com

This type of chart is what I was taught and makes far more sense, especially with the visual help at the top.

Kram · Mar 31, 2021

Ok now I understand iso fits... to admit my mistake :ashamed:

H7 is not +0.2mm (depending on size), it should be upto +0.01mm to +0.035mm. I was 10x out :laughing:

That means the first amazon set are no where near h7. However, they are still useful if you want a clearance hole, I'll still use them for that.
I'll check the H8 set when lathe is back together.

Brad93 · Mar 31, 2021

Check your tailstock alignment because that will throw a reamer out if the tailstock is out of line or ******

Hood · Mar 31, 2021

Brad93 said:
Check your tailstock alignment because that will throw a reamer out if the tailstock is out of line or ******

Or get yourself one of these

Pilgrim22 · Mar 31, 2021

Kram said:
Heres the links, not available from the same seller and tbe second price has gone up. It took quite a bit of searching to find the H8 set.
www.amazon.co.uk/gp/aw/d/B07V4747BW
www.amazon.co.uk/gp/aw/d/B07VWVH8XL

Cheers mate :thumbup:

123hotchef · Mar 31, 2021

Hood said:
Or get yourself one of these

View attachment 281827 View attachment 281828

what is it?

Reamers

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