what's the best way to ream out 1 1/16 holes to 1 1/4

[tackit]

(06-29-2014, 02:43 PM)Dr Stan Wrote:

(06-29-2014, 01:27 PM)tackit Wrote:

(06-29-2014, 11:41 AM)Dr Stan Wrote: What is the reason for enlarging the holes? If it is simply to have stronger pins would making some from a higher tensile strength steel achieve the same result?

Dr Stan I have given that thought but I'm not able to determine what type of steel would do the job... I'm going by what other presses use. I made a mistake when I cut the holes on the press, unfortunately one of the presses I was copying used smaller 1" pins not larger ones. Most presses on websites when I built the press didn't give pin sizes so I used what I thought was the right size. It works the way it is but it's not right and it bothers me.

I misspoke in my first post as I should have said shear strength rather than tensile strength. I spent some time researching and found most hitch pins (which are designed to resist shearing) are made from SAE 1039 or 4140 and hardened to Rc 40 give or take. Here's a site with some good examples: http://www.almabolt.com/pages/catalog/pins/hitch.htm

Keep in mind the shear strength is based on the physical properties of the material and the area of the cross section placed in shear.

Since most of us (at least I do not) have easy & free access to a good heat treating facility things like a pin placed in heavy stress really ought to be purchased, not turned out on the trusty lathe.

So even though you're increasing the cross section I'd still seriously consider buying pins that have been properly hardened and tempered. There are several sources such as McMaster, Grainger, etc and they certainly are proud of their hitch pins. So I'd check with the local Ag/Construction equipment dealer and a good automotive parts house for their prices.

BTW, nice press.

Thank you so much for the valuable information Dr Stan. I certainly will check out almabolt and the Ag/Construction equipment dealers around here as you suggested.

You saved me time as I haven't thought about what steel to use for the pins, instead I have been spending time on determining what's going to be the best way to enlarge the holes without destroying the accuracy I was able to get rotobroaching them. I spent a lot of time lining up the holes and hope I can keep the accuracy I achieved. The holes now are 1 1/16, the same OD as 3/4 pipe. Thanks for your nice press comment too.