Reaming en8

[Spikie1]

Anyone got any tips on reaming en8 as I'm struggling to get a nice finish the surface looks almost torn instead of nice smooth mirror Finish

 

[Ken I]

Spike, EN8 doesn't ream well - however if you take only a light cut with a sharp (newish) machine reamer using a high pressure / sulpherised lubricant you can get a good finish.

Are you using a machine reamer - a hand reamer has a tapered lead that cuts over a long area and tend to tear.

Ken

 

[steamer]

Also , don't take too much stock out with the reamer....bore the hole undersized by a say .003"....then ream it like Ken suggests, and don't spare the lubricant...you want to get the chips out of the cut zone.

Dave

 

[Spikie1]

Machine reamer and boring it out to size really isn't an option takes to much time and if was to bore it first I would end up finishing it to size I'll try a better lubricant I'm a production machinist so speed is of the essence for me I normally drill to within 1/4 mm then ream it using the normal White water/oil based lube I have a choice of a wd40 type lube and a much thicker cutting oil normally used for tapping

 

[Ken I]

Don't think too much of WD40 as a cutting lubricant (except for aluminium) - the "thick" tapping fluid sounds like a better bet.

What diameter reamer are we talking of here ?

Ken

 

[jonesie]

try drilling the hole .005 or.006 under and then take a new drill of the right size, and flatten off the cutting edges and use that instead of the reamer, with the flatten cutting edges it will cut like a reamer only less cutting edges good luck jonesie

 

[Spikie1]

20-30 mm reamers normally 150 deep to small for my availible boring bars

 

[woodchip85]

Check you reamers for damage on the cutting edges a slight pip or score mark on one and it will cause nothing but trouble, also get some rocol or similar cutting fluid/paste, I drill and ream en8/high carbon steels all day and only get a bad finish with a reamer when some idiot throws the reamers round and puts them back in the draws unprotected so they get damaged. En8 likes around 50% drill speed 120/140% feed of the drill you used as a good guideline, also try to machine feed the reamer and keep cleaning the swarf out regularly if you arn't already.

 

[Ken I]

Good points from Woodchip - Rocol lubricant (I always have a bottle to hand) and care / condition of reamers.

I ran a production run on EN8 (100's of thousands of parts over many years on Index C60 autos) reaming 23mm diameter x 20 deep - found 22.5 drill too small, eventually got some 22.9's for the job.

150mm deep - wow - that's deep - you need to be sure your alignment is spot on - alternatively use a floating holder for the reamer (self aligning).

Ken