Reamers

[Griffin]

First post this so not sure what I’m doing here but…….


I’m building the PM #5 bottle engine at the moment Igot from santa and reached the stage where I needed to drill crank journals to5/16 or 0.312 thou, so I worked up to19/64 and ordered a reamer from Arc euro to finish it to size, when it arrivedI find its tapered, starting at 0.301 to 0.315, I’ve not seen this before so Iwaited till Monday morning phoned them up and to my surprise was told therelike that, however if that’s the case how do you ream a blind hole and whatshould I have ordered? or am I just going loopy in my old age :wall:

 

[Lakc]

That size doesnt match any taper reamers I could find on this side of the pond.
Things may be different over there, but all the chucking reamers I have bought have no taper aside from the first .020 or so.
If you cant pass the whole length of the reamer through the part, you have to grind it off to the right size, or bore it out.

 

[Tin Falcon]

make a d bit reamer . take a 5/6 piece of silver steel grind off 1/2 the diameter at the end about 1 diameter s length back exact length not critical. try that not sur if there is such a thing as a bottoming reamer.
Tin

 

[GWRdriver]

This doesn't smell right. I looked at their listings and they don't list anything but parallel reamers and that "they're all like that" isn't your problem. A tapered reamer does you no good, now or later. I'd ask for a replacement and if they can't supply a truly parallel reamer I'd have my money back.

There is such a thing as a Bridge Reamer which was used in ship building and structural steel erection to size and align rivet and bolt holes. These have a curving taper away from the nose finally straightening out to the nominal size about half-way down the cutter, but these tend to be quite large, 3/4" and above, although they may very well be made smaller.

 

[Arrak_Thumrs]

The difference between a "hand reamer" and a "chucking reamer":

A chucking reamer is meant to only be machine driven in a solid set-up. It cuts only on its sharply beveled end. The diameter remains constant for the full length of the reamer.

A hand reamer is used by hand driven by a square socket wrench (i.e. tap wrench). It has a minor taper ground back for a noticeable length at the beginning. This taper is present to aid starting and advancing the reamer parallel to the bore. It can also help avoid reaming out of round holes by its centering effect and reinforcement of axial orientation. Without it, the tool is more likely to catch and "dig in" during use, ruining your hole.

Arc Euro Trade lists only "parallel hand reamers." In this instance, the term "parallel" refers to the flutes. Notice the picture. Either type of reamer can be had with parallel (straight) flutes or helical (spiral) flutes. Arc Euro Trade only lists the former.

 

[Griffin]

OK,

Manythanks guy’s for taking the time to reply, it is as I suspected and your right GW,“it don’t smell right” but I am puzzled as to why they would pull such a stunt,and that’s why I asked in here, Tin, I will give it a try just to see if I cando it, might even post some pictures of the bottle engine some time if I can work out how,

Mark