Coventry Adjustable reamers

[Shox Dr]

Can anyone tell me what the window of adjustment is on a Coventry Adjustable reamer. Looking at buying one for the tailstock refurb.



An adjustable one will allow me to "sneak" up on the size required, opposed to using a fixed size that may be either too little or too much, as fixed reamers always cut 1-2thou over. And they are easier to source

 

[madkayaker]

Remind me Monday and will look at work and tell you

 

[Shox Dr]

Cheers

 

[madkayaker]

What size are you aiming for?

 

[Shox Dr]

well the quill measures in at 41.97mm. Not sure on how much I need over that for a nice sliding fit

 

[madkayaker]

Ok gives me an idea

 

[graffian]

An adjustable one will allow me to "sneak" up on the size required, opposed to using a fixed size that may be either too little or too much, as fixed reamers always cut 1-2thou over. And they are easier to source

I was using a david brown reamer this afternoon and thought about your
tailstock. David Brown or Cogsdill reamers would probably work.

 

[Shox Dr]

So how are they adjustable I cant find any info at all

 

[inchpincher]

So close and yet so far, I thought "I've got just what he needs in the bottom of my toolbox...”

Turns out it's 1 3/8" - 1 1/2" so about 4mm shy, sorry

 

[Shox Dr]

No need to apologise. Thanks for looking

 

[Tigman]

Ive got a big box full of adjustable reamers , never used ! double ended things ! if you would likey for beer tokens let me know !

 

[scott0031]

Hi Mr shox, hope you are well,

Firstly if a reamer is cutting oversize as you mention in your first post, then you are doing something wrong with the process, reamers cut size for size.

second, adjustable reamers work with multiple blades running on the body which has tapered slots ground into it. The blades are wound up on a thread as such progress up the taper and expand or retracts as necessary.

Fourth, the info i can get on that size of reamer the adjustment is 38-46 mm 1 1/2 - 1 13/16 so that size will do you.


Fifth, This one is a warning! Be wary of second hand reamers. This style of reamer tends to be used more by mechanical type engineers and not machine shop engineers, as such they are often not treated as per a machine shop. They get laid in boxes knocked about etc etc, this means the blades are often rounded off or damaged. The reason to be wary is because bronze has a nasty habit of closing up upon itself, A worn reamer could make this a hell of a lot worse. If you get this closing up or have a problem it will seize and can be exceptionally difficult to release. If you go down this route if you feel any resistance to the the normal cutting you would expect, get the reamer out immediately don't wait until gets dead tight, as you will have a problem. This scenario can also still happen with a brand new reamer in bronze, so be warned.

That said, this is one of the worst cases that can happen with bronze, but doesn't mean it will be a problem, its one of those materials that can be fine or give you a severe headache at times.

My preference would still be to bore it as you have more control over the job.



Kind regards,


Scott

 

[Shox Dr]

Scott, thanks for your input.

I was under the impression a reamer cut to size, but reading the Presto book, suggests different: They having far more experience than I, I took it as word. Also finding a reamer in good condition of correct size, will be hard: hence the adjustable route

I've a set of Herbert adjustable hand reamers upto H12. They were my granddads, and are in first class condition. And I'm not in the habit of mistreating tools. However this job requires a H15

I've machined a fair bit of Brass, and I'm aware of it nippin' up if you are not careful, And was under no illusions Bronze would be any different.

I'm also with you in believing I can get the bore to size with the boring, I'm just been cautious.

Once again thanks for the reminders.