Dowel Pin Hole Preparation

[pearldiver]

I'm going to install a 1/8 dowel pin. I was able to find a 1/8 dowel pin reamer that has a decimal size of .1230 . The nearest drill size I have found for that size is #31 ( .1200 ). Do you suppose I could ream out a .1200 hole with a .1230 reamer without destroying the reamer? The diameter tolerance of the reamer is only .0000-.0002

[christinandavid]

Hi,

Are you talking about a parallel pin/hole? If so you probably could do with leaving more metal in for the reamer to cut efficiently. 2.8mm (.110") to 3mm hole (.118") max.

DP

[tobyaxis]

As mentioned above. Common Machining Practice is to leave .015 Diameter or .0075 Radial for finish Reaming.

[pearldiver]

Originally Posted by christinandavid Hi, Are you talking about a parallel pin/hole? If so you probably could do with leaving more metal in for the reamer to cut efficiently. 2.8mm (.110") to 3mm hole (.118") max. DP

Hi David, I'm quite confuse on reamers. I wish there is like a tapping chart werein there is an appropriate drill size for each tap. This is the first time that I'll be using a reamer and I just want to make sure that I wont end up in destroying the reamer because the hole is to small to ream

[tobyaxis]

Originally Posted by pearldiver Hi David, I'm quite confuse on reamers. I wish there is like a tapping chart werein there is an appropriate drill size for each tap. This is the first time that I'll be using a reamer and I just want to make sure that I wont end up in destroying the reamer because the hole is to small to ream

Look at the above post. The Standard Practice is there.

[Hennessy]

Don't forget to indicate the reamer in. The reamer needs to be running true to the spindle to insure that it cuts a round hole. If the reamer is wobbling it will cut an egg shaped hole and will cause fit problems. As far as the drilled hole size goes I generally drill .010 to .015 under the nominal diameter then ream to size. so for your reamer with a .123 diameter I would go with a drill between 7/64 and a #33. I also use a bigger drill the deeper the hole is. just make sure you leave enough for the reamer to cut.

Hennessy

[tobyaxis]

Originally Posted by Hennessy Don't forget to indicate the reamer in. The reamer needs to be running true to the spindle to insure that it cuts a round hole. If the reamer is wobbling it will cut an egg shaped hole and will cause fit problems. As far as the drilled hole size goes I generally drill .010 to .015 under the nominal diameter then ream to size. so for your reamer with a .123 diameter I would go with a drill between 7/64 and a #33. I also use a bigger drill the deeper the hole is. just make sure you leave enough for the reamer to cut. Hennessy

If you can move a reamer while it is tight in a collet what makes you think it won't move back after one cut??

If a Reamer Shank is Bent, it's not any good, hence your egging the bore. The Reamer Shank when straight will find it's own center and come out round and straight.

Same applies to drills. If the shank is bent, do not use it, go find a straight one.

[RICHARD ZASTROW]

pearldiver, you might try http://www.yankeereamer.com/tech_info

Dick Z

for some reason, I can't get the url to work. probably something I did. Try to google it yourself, there is a nice chart there.

[christinandavid]

Hi,

One thing that is also critical for the size of your finished hole is the condition of your reamer. If you have a 1/8th reamer that measures .123 then it sounds like it is very worn through overuse/stoning. A badly worn reamer will not necessarily cut small!

If it measures size/looks in better condition at the back end, chop off the end and regrind a new lead onto it (this has to be quite accurate).

Have found that running reamers dead slow (slower than recommended) and flooding with coolant/oil can make them last a lot longer.

To prevent premature wear on inconels and titanium alloys I also leave a lot more metal in for reamer to cut (at least 10% of finished hole size).

To ensure reamer starts on position and to give it a better chance of cutting size, pilot the top of the hole a couple of millimeters deep with same size slot drill (check it runs true).

DP

[tobyaxis]

Hanibal makes great reamers.

HANNIBAL CARBIDE TOOL, INC.

[mactec54]

Hi pearldiver

This may help
http://www.yankeereamer.com/

[easymike29]

I doubt that you can press a .125 dowel pin into a .123 dia. hole. I am assuming heat treated steel.

Gene