reamer question

[brokenflint]

What type of reamers are generally used on locks?  A straight flute or spiral flute?  any particulars needed to be known about reamers?  HSS good enough to order?

Broke

[billd]

HHS is fine.  Carbide is too brittle for hand work.  I have access to all kinds of reamers but I always grab an adjustable chucking reamer.  Meaning is has a straight shank you can put in a drill press and it is adjustable a few thousands.  Because it's adjustable, it's only available in straight flute.   The advantage is you can cut the hole undersize and adjust it and ream a second time.  Just more assurance your hole is correct. 

Also, when you turn the tumbler a few thousands over or under you can adjust the reamer to match.  But that never happens. 

Bill

[Dphariss]

What type of reamers are generally used on locks?  A straight flute or spiral flute?  any particulars needed to be known about reamers?  HSS good enough to order?

Broke

HSS is perfect. Carbide is for special uses. There are coatings that work well with materials like stainless and in high production work but a plain HSS reamer is fine for our purposes.
I use what ever I have that is the right size. Spiral flutes are generally meant to clear chips better in blind holes etc. Not really needed in lock making.
You can buy chucking reamers is .001" increments from MSC. But note that sharp reamers generally cut a little larger so its best to have a spread of sizes for a given hole.

I have an expansion reamer too but it seems to be on permanent loan It takes longer to use than just using a reamer that will cut the hole needed. But at times they are really nice to have.

Dan

[Daryl]

Varous reamers can be purchased from pacifictoolandgauge.com  Dave Kiff, the proprietor is a good guy and pricing is reasonable.

[brokenflint]

I'm doing my homework     Billd told me to use machine screw drill bits, as they where more resistant to flex and wobble, so I'll be looking those up today so see what all the fuss is about LOL.  I'm not a machinist by any stretch of the imagination, so thanks all

Broke

[flehto]

I use both straight and spiral fluted reamers and pre- drill the smaller holes 1/64" undersize and the larger holes 1/32" undersize and then ream.  Reamers are best run at slow speeds like ctsks. Twist drills can be made into "reamers" by grinding a radius in lieu of a sharp corner at the juncture of the flute and cuttting lip. ...Fred

[Dphariss]

I'm doing my homework     Billd told me to use machine screw drill bits, as they where more resistant to flex and wobble, so I'll be looking those up today so see what all the fuss is about LOL.  I'm not a machinist by any stretch of the imagination, so thanks all

Broke

The problem with drills is that they drill to about the size they are supposed to.
With a pilot hole it can be pretty close. Without it may be significantly oversize.
Dan

[Brian]

Is there any rule of thumb with regards to the size of the pilot hole as compared to the finished hole, or how many "steps" you take to get from pilot hole to finished hole?  For example, if you wanted a finished hole of 11/32.  Would you do a pilot hole of say 1/8", then follow that with a 3/16", and then finish with the 11/32"?  Or would you just drill the 1/8" and then hit it with the 11/32?

[billd]

A quality drill drill should only drill about .002 bigger than the drill size,
but there are many variables.
1. the spindle bearings in the drill press are in good shape.
2. The part is firmly clamped down.
3. The metal being drilled is thicker than the diameter of the drill or a backer plate is attached behind what you are drilling.

Common problems with drilled holes are out of round or triangular shaped.   This is caused by the part being drilled being thinner than the drill diameter.  The part can actually move back and forth within the flutes.

Oversize holes are commonly caused by resharpened drill that has the point off center or the web thinned incorrectly.  A properly sharpened drill has no more then .002 TIR on the point and less on the flute heigth.  If your sharpening by hand you will never see these measurments.


Bill

[Steve-In]

For a really smooth hole use a left hand spiral, right hand cut reamer.  HSS is fine.   It usually leaves a finish like glass.  Run it slow and clean the flutes out as you go.  The problem with reamers is they tend to follow the pilot hole.  Even by stepping up the drill sizes they still tend to follow the original hole.  A small stiff spot drill will help the drill run center.
A pilot drill does not need to be much larger than the drill tip.  A small drill is more likely to lead off though.  If you can find the correct size in a mill you can straighten out the hole for better location.  If your spindle has a lot of play in the spindle they will grab as will twist drills.

[Dphariss]

A quality drill drill should only drill about .002 bigger than the drill size,
but there are many variables.
1. the spindle bearings in the drill press are in good shape.
2. The part is firmly clamped down.
3. The metal being drilled is thicker than the diameter of the drill or a backer plate is attached behind what you are drilling.

Common problems with drilled holes are out of round or triangular shaped.   This is caused by the part being drilled being thinner than the drill diameter.  The part can actually move back and forth within the flutes.

Oversize holes are commonly caused by resharpened drill that has the point off center or the web thinned incorrectly.  A properly sharpened drill has no more then .002 TIR on the point and less on the flute heigth.  If your sharpening by hand you will never see these measurments.


Bill

This is perfectly true. Less than perfect drills do all sorts of strange things. How concerned I am about this depends on what I am doing at the time.
If trying for an interference fit .002" over (or under for that matter) causes "problems". Thus reamers.

Dan

[P.W.Berkuta]

If I want to keep a "as true to size" hole as possable I drill .010 under size then use a drill bit of the finish hole size I am looking for. It "should end up within .003 of the drill bit. If I use a reamer with lube then it should end up within .001 of the reamer. All is dependent upon the drill press condition, drill bit, or reamer --- if you want "dead-nuts" use a quality milling machine and a new reamer - just my experience D ;.