The effect of lubrication on reaming tolerance

[Benny AvelinParticipant @bennyavelin86238]

I have heard on many places that when reaming the hole will get bigger with cutting oil as opposed to soluble oil. I never really found a good source for this, but today I found this old PhD Thesis where the author makes a summary of the engineering research about this particular issue.

The paper can be found here and the relevant information starts on page 29

**LINK**

I thought this could be interesting for someone, unless it is already well known and so on…

[Benny AvelinParticipant @bennyavelin86238]

[Martin ConnellyParticipant @martinconnelly55370]

I would suggest that for the typical person the different hole sizes stated are to all intents and purposes the same. The variation is measured in millionths of an inch. This is far below what the average machinist would consider acceptable variations in hole size.

Martin

[ronan walshParticipant @ronanwalsh98054]

Yes lubrication does have an effect. As apprentice's we were puzzled by holes not being the fit we wanted them to be and blamed the reamer, but we were told the cutting oil, either oil or soluble oil affects the clearance. Stefan Gotteswinter on youtube, who i recommend everyone subscribes to, demonstrates this in one of his excellent videos.

https://www.youtube.com/user/syyl

Thanks Benny.

[Benny AvelinParticipant @bennyavelin86238]

Martin you are correct. Microinch would be incredibly small, but what kind of reamer makes a hole within 10 microinch?

It turns out the author made an error of units, the charts are taken from a Japanese report. Although the report is in Japanese, and I can't read Japanese, I managed to conclude that they use mm and not inch and therefore the measurements should be micrometer. 10 micrometers is 0.01mm which is noticeable when it comes to fit, secondly it can be concluded that the tests they conducted resulted in holes that where undersized when certain cutting fluids where used. This is great info if one wants a tight fit with a normal reamer.

[not done it yetParticipant @notdoneityet]

https://www.youtube.com/user/syyl

Which one? There are hundreds – well, lots of dozens!

[Martin ConnellyParticipant @martinconnelly55370]

The other thing that caught my attention in the report was the rpm used. At the high speed used heating of the tool can occur. In this case the cutting fluid with the best cooling properties will produce smaller holes than ones that let the tool heat up.

Martin

[Tony Pratt 1Participant @tonypratt1]

Posted by Martin Connelly on 17/03/2017 13:19:41:

I would suggest that for the typical person the different hole sizes stated are to all intents and purposes the same. The variation is measured in millionths of an inch. This is far below what the average machinist would consider acceptable variations in hole size.

Martin

LOL, 'variation is measured in millionths of an inch', have you actually read your statement before posting? From practical experience the type of lubrication used in reaming does make a noticeable difference to hole size.

Tony

 

Edited By Tony Pratt 1 on 17/03/2017 20:15:15

[ronan walshParticipant @ronanwalsh98054]

Posted by not done it yet on 17/03/2017 19:13:28:

https://www.youtube.com/user/syyl

Which one? There are hundreds – well, lots of dozens!

The one in the link below, about 26mins in.

[vintagengineerParticipant @vintagengineer]

A trick to make a machine reamer cut oversize is to insert a piece of shim to one side of the reamer.

[John Stevenson 1Participant @johnstevenson1]

It's not an old wives tale, it does work and I have posted about this before on this and other forums.

Tightest hole you can get use neat trike, after than soluble oil ad then neat cutting oil.

To get a reamer to cut undersize rub a hardened dowel pin down the flutes, top to bottom. To get it back on size again rub the same dowel pin down the front face of the flutes. Top to bottom.

To stop a machine reamer leaving circular tram lines in the work which is caused by one tooth being higher than the others, take a fine stone and slightly round the front chamfers were they meet the flutes.

You would never use a lathe tool ground to a sharp angle without breaking the corner with a stone but reamers are sent out this way as it's cheaper.

[Neil LickfoldParticipant @neillickfold44316]

Castor oil can allow you to ream a hole slightly smaller than the reamer itself. Castor is one of a few products that allow parts that would be a press fit to be a slide fit, to about 0.005mm to 0.008mm in interference fit in a 12mm to 20mm hole.

Neil

[Martin ConnellyParticipant @martinconnelly55370]

Tony, I was commenting on the linked document only, nothing else. His graphic is labeled plus and minus 10 micro inches. For the size of hole he is using this is less than the variation caused by a 1 degree C change in temperature. The cooling effect of lubricants is important, using hand tools can raise the working temperature of the tool significantly. I do not doubt the differences that people are reporting but do think the working temperature of tool and workpiece are very important to precise hole sizing.

Martin

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Neil Lickfold on 18/03/2017 00:45:45:

Castor oil can allow you to ream a hole slightly smaller than the reamer itself.

.

Neil,

I'm struggling to understand how that works …

Does it presume the use of a straight-flute reamer, and an odd number of flutes? … or am I missing a trick?

MichaelG.

 

 

Edited By Michael Gilligan on 18/03/2017 08:59:35

[Benny AvelinParticipant @bennyavelin86238]

Posted by Michael Gilligan on 18/03/2017 08:54:09:

Posted by Neil Lickfold on 18/03/2017 00:45:45:

Castor oil can allow you to ream a hole slightly smaller than the reamer itself.

.

Neil,

I'm struggling to understand how that works …

Does it presume the use of a straight-flute reamer, and an odd number of flutes? … or am I missing a trick?

MichaelG.

Edited By Michael Gilligan on 18/03/2017 08:59:35

I would guess spring back in the material?

[Benny AvelinParticipant @bennyavelin86238]

Posted by John Stevenson on 18/03/2017 00:21:58:

It's not an old wives tale, it does work and I have posted about this before on this and other forums.

Tightest hole you can get use neat trike, after than soluble oil ad then neat cutting oil.

To get a reamer to cut undersize rub a hardened dowel pin down the flutes, top to bottom. To get it back on size again rub the same dowel pin down the front face of the flutes. Top to bottom.

To stop a machine reamer leaving circular tram lines in the work which is caused by one tooth being higher than the others, take a fine stone and slightly round the front chamfers were they meet the flutes.

You would never use a lathe tool ground to a sharp angle without breaking the corner with a stone but reamers are sent out this way as it's cheaper.

Thank you for those great tips. But forgive my non-native english, what is neat trike?

[MuzzerParticipant @muzzer]

Trichlorethylene.

[David ColwillParticipant @davidcolwill19261]

I too have heard this from more than one source. Just for the sake of completeness I decided to nip into the workshop and try it. I used a piece of en8, which was drilled to 19.5 mm and then reamed with a 20 mm machine reamer.

Obviously I used the same sequence of drills and the same speeds. For the soluble oil i mixed a thin (5%) mix of Hysol XF for the thick oil I used SW68 slideway oil (cos it was next to the lathe).

I measured the resulting holes with a Bowers 3 point bore micrometer. To be honest I wasn't expecting much if any difference but was surprised to see that the hole reamed with the thicker oil was .02 mm bigger than the one done with soluble oil. I fiddled around with the test pieces and took measurements by rotating the parts around and yes the results were consistent.

Regards.

David.

[MuzzerParticipant @muzzer]

Did you look at the surface finish? It's easy to focus on the measurement of the diameter but if the main difference is actually the surface roughness, it's sort of questionable just where the diameter is measured from – and if it really is different in the way we are talking about it. I could imagine that for the sort of accuracies and processes we are using, that could be more likely to be affected by the lubrication used. In the interests of science, I'd be interested to cut open the test samples and measure the surface roughness.

Murray

[David ColwillParticipant @davidcolwill19261]

Good point.

I hadn't looked at the surface finish but have now. I can't see any difference really. I tried to take some photos but they don't show up very well. I don't have any accurate way of measuring surface roughness so here endeth the experiment but I'm sure it will come in handy.

David.

[Benny AvelinParticipant @bennyavelin86238]

David and Murray, at least the report mentions that the surface roughness is less with soluble oil. So not only does the hole get smaller but also finer, perhaps its due to an increased level of burnishing.

So, Murray if you wish to try in the interest of science, I could not be more thrilled.

[Neil LickfoldParticipant @neillickfold44316]

Trichlorethylene mixed 50% with castor was sold as Glow cut right up till the early 1980's.

I am not sure what allows castor oil to make tight parts assemble. Model diesel engines work because of castor oil, allows an over size piston to go to TDC without too much friction and without wearing or causing gauling of the materials. It also allows the contra piston to be fitted and then can be adjusted up and down, also without gauling or seizing.

Neil

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Neil Lickfold on 19/03/2017 09:45:34:

I am not sure what allows castor oil to make tight parts assemble. …

.

Thanks for responding, Neil

Your original comment remains intriguing, so I hope others might be able to explain how: "Castor oil can allow you to ream a hole slightly smaller than the reamer itself."

MichaelG.

Edited By Michael Gilligan on 19/03/2017 11:14:07

[John Stevenson 1Participant @johnstevenson1]

Posted by Neil Lickfold on 19/03/2017 09:45:34:

Trichlorethylene mixed 50% with castor was sold as Glow cut right up till the early 1980's.

Neil

.

?? Trichorethylene ??

Do you mean ether as trike is non-flammable ?

Just asking as I have no expertise on small aero diesels

[Raymond AndersonParticipant @raymondanderson34407]

Unless he means Trichlorethane ? which is certainly flammable [ very ]

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