Reamers - what are the basics?

[Beanwood]

What material are you trying to ream?

Mild steel at the moment

 

[Beanwood]

It's not that it won't be centered.

The hole won't be as round as if you'd gone straight in with the 3.9mm.

As i've said above and someone else also pointed out 2-3% is the recommended reaming size. 2% would give a tighter fit normally.
Also a difference if you use lubrication and what type. Soluble coolant will cut a different size hole to neat cutting oil.

Forget tolerance classes of the reamer that's going to make zero diffference.

Your pillar drill likely has more runout in the spindle that the difference between tolerance classes and if you're holding the reamer with a drill chuck it has 10x that amount.

Right - off on another shopping trip.

Would you suggest a 3.9 twist drill, or a 5/32 Slot drill?

I do need some more cutting lubricant - would Rocol work for this, and hopefully the lathe as well?

I'm using a hand reamer in a tap wrench - which could be another cause of the problem...

 

[bricol]

I'm all for DIY, make do and mend, etc, but just sometimes . . .

Punch and Die components - DAYTON PROGRESS

Punch and Die components from DAYTON PROGRESS - punch systems and die buttons in various lengths and diameters ► Learn more!

www.daytonprogress.de

Die Sets | Rear Centre and Four Pillar Precision Die Set

Buy Die Sets and Precision Die Sets from stock. Visit WDS Components for Die Sets at highly competitive prices.

www.wdscomponents.com

 

[Beanwood]

I'm all for DIY, make do and mend, etc, but just sometimes . . .

Punch and Die components - DAYTON PROGRESS

Punch and Die components from DAYTON PROGRESS - punch systems and die buttons in various lengths and diameters ► Learn more!

www.daytonprogress.de

Die Sets | Rear Centre and Four Pillar Precision Die Set

Buy Die Sets and Precision Die Sets from stock. Visit WDS Components for Die Sets at highly competitive prices.

www.wdscomponents.com

Yes, I think you mentioned this before - but my previous enquiries came back at over £1k....
Still undeterred, I have just tried another company to see what can be done. From them, it seems that a single punch is easy - but the particular pattern of 6 or 8 punches is somewhat more difficult, requiring a specialist press tool manufacturer.

 

[Misterg]

drill the final 3.8 on the pillar drill, prior to hand reaming it.

The material I'm cutting is circa 0.2mm or less

Mild steel

When inserting, then turning the 4mm reamer (Having liberally luricated it) there were several loud 'cracks' which sounded just like a tap snapping.

That material is extremely thin. I'm not an expert at all, but I can't help thinking that you could only get away with taking the tiniest sliver off with a reamer, or the material is going to buckle and let the reamer dig in (which may have been what your 'cracking' sensation was. I suspect that the situation would be exacerbated by hand-holding the reamer - on thicker stuff, there's enough depth to act as a sort of pilot for the tapered end of the reamer to guide it in square, but without that, it's almost certainly going to end up cock-eyed.

I don't know how many you have to make. If not too many, I'd suggest clamping the parts tightly between two sacrificial plates (maybe 5mm thick aluminium each side) and drilling/reaming through the whole lot.

 

[Beanwood]

That material is extremely thin. I'm not an expert at all, but I can't help thinking that you could only get away with taking the tiniest sliver off with a reamer, or the material is going to buckle and let the reamer dig in (which may have been what your 'cracking' sensation was. I suspect that the situation would be exacerbated by hand-holding the reamer - on thicker stuff, there's enough depth to act as a sort of pilot for the tapered end of the reamer to guide it in square, but without that, it's almost certainly going to end up cock-eyed.

I don't know how many you have to make. If not too many, I'd suggest clamping the parts tightly between two sacrificial plates (maybe 5mm thick aluminium each side) and drilling/reaming through the whole lot.

Thanks @Misterg - I think I confused things there. The mild steel I'm trying to drill/ream at the moment is about 5mm. Once this has been proven, I'll be making the holes into punch and dies of about 10mm.

The END product I will be punching through (Of no consequence to this - I don't even know why I mentioned it) will be 0.2mm

 

[Misterg]

The mild steel I'm trying to drill/ream at the moment is about 5mm

Oops! Sorry for the misunderstanding

5mm should be just fine

 

[Beanwood]

If you can wait i'll have a look at the workshop and see if i have some Dormer 3.9mm drills.
I may even have a quality 4.0mm reamer.

What sort of mill do you have?

If it's of good quality i would drill and ream in the mill.

As Clive said ideally you want a floating chuck for holding reamers. But i think for the small size of the bore you'll be okay if you can hold the reamer accurately in a collet

Thanks - that's very kind - I have just bought a couple of Dormer 3.9's from Cromwell to get me a step closer.

My mill is a little old Dore-Westbury. It seems solid enough, and the drill is an old Atlas CopCo Mill/Drill so should be fairly solid also. I've never thought to check the run out.

 

[Beanwood]

Dormer 3.9 arrived today- after a quick test tonight no more catching when using the reamer.
The silver steel 4mm rod appears looser than I was hoping- something to look at later in the week…

 

[pressbrake1]

What kind of fit are you trying to achieve?

 

[sako243]

What kind of fit are you trying to achieve?

Not a fit per se as he's making the die for a punch and die. My understanding is that it's initially a 5mm thick die (for trying out) then going to 10mm for the final version. Punching through 0.2mm thick stock.

 

[Beanwood]

Are you still using the pillar drill?

Through once with the reamer then straight out. No running it in and out?

Yes - stil using the drill press at the moment - I couldn't find a 3.9mm threaded slot drill for my clarkson autolock holder thing.
Yes - definitely only once through wth the reamer - it didn't take much of a twist before it 'fell' through, (Caught obviously by me holding the tap wrench) and not pulled back up through the hole once made.

What kind of fit are you trying to achieve?

Tight slip fit although I don't know the technical term? If I've understood correctly, the punch needs to be pretty close so it shears, rather than drags when entering the die. I'm playing with tolerances on a 5/32 Silver Steel rod and a 4 mm hole being 'about right'.

Not a fit per se as he's making the die for a punch and die. My understanding is that it's initially a 5mm thick die (for trying out) then going to 10mm for the final version. Punching through 0.2mm thick stock.

Exactly so - thanks @sako243 - far more eloquently than I've put it. (The 5mm is just because I had some spare - and not much spare of the 10mm.)

 

[pressbrake1]

I’ll do a sketch later on making punch and die for thin material

 

[Beanwood]

I’ll do a sketch later on making punch and die for thin material

Thank you.

 

[pressbrake1]

For tight fit I use an old reamer or gently blunt one .
Accuracy isn’t a given it take time and experience