Reamering cast iron – lubrication

[Martin DowingParticipant @martindowing58466]

To lubricate or not to lubricate, that is a question?

Edited By Martin Dowing on 28/02/2018 08:06:03

[Martin DowingParticipant @martindowing58466]

[Brian HParticipant @brianh50089]

Definitely not lubricate! The reamer will cut dry but any lubrication will make it slip.

Brian

[John HaineParticipant @johnhaine32865]

No, and reaming. But take it slow and clear chips frequently.

[Grindstone CowboyParticipant @grindstonecowboy]

I would certainly go with the advice of the experienced members of the forum.

However…. I did read in an old article (c. 1905) that reaming with oil makes a smaller hole than reaming dry, but it did NOT specify whether that applied to cast iron. Possibly the built-in lubrication of cast iron makes it irrelevant, but I was wondering if this was actually true and why it might be?

All I can think is that dry reaming cause the non-cutting edge on one side to drag a miniscule amount and force the cutting edge on the opposite side to take a bigger "bite", for want of a better word.

Is it true, and if so, is my theory correct? Apologies for hi-jacking the thread, but I thought it was kind of relevant to Martin's question.

Rob

[Brian HParticipant @brianh50089]

Bob, there isn't a non-cutting edge, all edges will cut when the reamer is turned in the correct direction.

Brian

[Jon GibbsParticipant @jongibbs59756]

I seem to remember Stefan Gotteswinter saying that lubricating with cutting oil leads to a larger reamed hole than using water soluble oil but this wasn't in cast iron.

I can't find the actual discussion now but there is something at 14'30" in this video **LINK**

…where he's using water soluble oil and a very close bored starting hole for the snug suction fit on a dowel pin.

HTH

[Edit: Just found this https://ttu-ir.tdl.org/ttu-ir/bitstream/handle/2346/15032/31295005186092.pdf?sequence=1. See pages 29 onwards – a whole PhD thesis on reaming!

Dry leads to the biggest holes in general and less viscous oils lead to less oversize with soluble oils leading to best surface finish and potentially undersize holes.]

Jon

 

Edited By Jon Gibbs on 28/02/2018 09:32:22

Edited By Jon Gibbs on 28/02/2018 09:43:11

[larry PhelanParticipant @larryphelan54019]

I understood that cast iron was always machined dry ??

[John HinkleyParticipant @johnhinkley26699]

Jon Gibbs' reference to Stefan Gotteswinter's video is when he's making his cylindrical grinding attachment, here:

**LINK**

at about 26 minutes et seq. As Jon said, that isn't in cast iron, however, and I would not use any form of lubrication myself on such material.

John H

Edited By John Hinkley on 28/02/2018 09:44:44

Edited By John Hinkley on 28/02/2018 09:45:20

[Jon GibbsParticipant @jongibbs59756]

Posted by John Hinkley on 28/02/2018 09:44:02:

Jon Gibbs' reference to Stefan Gotteswinter's video is when he's making his cylindrical grinding attachment, here:

**LINK**

at about 26 minutes et seq. As Jon said, that isn't in cast iron, however, and I would not use any form of lubrication myself on such material.

Thanks John.

[Martin DowingParticipant @martindowing58466]

Hi,

Many thanks for comments.

Have decided not to lubricate, like usual with cast iron.

What diameter of drill would you use before reaming to 4mm? I suspect that 3.8-3.9mm is correct.

With larger diameters (6-20mm) I was always using drill 0.2mm smaller, at 20-30mm it was 0.3mm smaller but I have never reamed such a piddly little thing.

Martin

[Grindstone CowboyParticipant @grindstonecowboy]

Thanks for all the information, chaps, there's always something new to learn

[mechman48Participant @mechman48]

Ream dry. Do you need to ream such a small hole? you may find that drilling with a 3.9mm drill will give you 4mm dia. hole taking in to account any run out / lip length discrepancy in the drill. If you must ream this small size the I suggest you go to a 3.8mm drill but take it slow & clear out chips frequently, this will give you the max allowance of .008".

George.

[mechman48Participant @mechman48]

FYI…

​Ref… Presto Engineers Cutting Tools.

George.

Edited By mechman48 on 28/02/2018 11:12:51

[Martin DowingParticipant @martindowing58466]

Many thanks,

Now I know how to proceed with that.

Martin

[Speedy Builder5Participant @speedybuilder5]

There are several different types of cast iron. We are probably talking about Grey Cast Iron here which I would ream dry, however the much harder White cast iron (Drain pipes ?), I would use a lubricant to protect the reamer.
Other types include Spheroidial Cast Iron, Malleable Iron, Ductile Iron and probably more besides.
BobH

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