Help! > Mistakes, muckups, and dangerous behaviour

dislexia oops, oops and oops again!

(1/5) > >>

DavidF:
    Not a good day in the shop thats for sure. Im working on making a small jig that will mount to the T slot on my mill for drilling connecting rods. The idea is to have a tool that I can use to drill the 4-40 rod bolts into the rod by hand then mount it to the table and drill and ream the rod journal and wrist pin. I have to make a good number of rods so I figured that a jig was in order. So today I was working on the steel drill and tap guides for the rod bolts and things didnt go well at all. First off I mis read my dro because when I wrote the dimension on a piece of paper I wrote it as 2.125 the funny thing is the dimension was actually .225 (little math error) and when I set it up to drill I did it at .2125  :slap: Ok theres on wild mix up that Im surprised im telling you...  Then I decided to put lay out lines on the second part so I could visually see things were in the mark. Things were going good, center drilled both holes, drilled thru the first hole, started drilling thru the second hole and "CRUNCH"  :censored: :censored: :censored: Ok no big deal there is enough bit sticking out that removal was easy. so I re touched it with the center drill and figured I would drill tru a bit smaller then open up the hole "CRUNCH"  :censored: :Mad: :censored: :cussing: are you kidding me!!!  Ok removed that piece of drill bit re touched with center drill and re sharpened broken drill bit, spead up mill and had at her again...I made it thru, but the holes are off about .005" and I would like to be closer than that by far.  Any suggestins on drilling small straight holes within .0005"  Im A bit aggrivated and going to take a break until tomorrow..

DaveH:
David,
Sometimes it is best to center drill then go through with the drill without moving the workpiece. Also the drill needs to be correctly and accurately ground to achieve a straight hole.
 :cheers:
DaveH

DavidF:
DaveH,  yes probably not best to move around from center drilling the drilling.. I'm going thru the things I did today in my head and rethinking the process, I don't think me moving the x,y axis had anything to do with it. I only moved the x axis and I'm off on the y axis equally on both holes. I did however have to lower the knee to fit the drill chuck and drill bit after I indicated the part using a collet.  My mill is pretty clunky so I'm thinking this is where the error is...
  I guess to fix it I could use and end mill to punch the holes oversized then make some drill bushings from drill rod on the lathe to fix the problem. Probably a good idea?
  How do you guys make your connecting rods for your engines, from step 1...?  Maybe I'm going about things the entirely wrong way...

swilliams:
Hi Dave
Maybe you need to tighten up some of the gib adjustments on your mill? Things can move around quite a bit when the knee and cross slide gibs are loose.  If you have a lock on the knee using that could help.

Just a thought
Steve

DavidF:
Gibs are pretty snug on x y,  knee is a bit loose but I all ways lock it up. I'm thinking it would be a good idea to do some work to the mill and also go thru my drill chucks.  I know I do have an issue with the spindle run out that I have been trying to avoid getting into for years. Anyone ever re turn/grind  the R 8 taper in thier spindle?   Going to search the web on this one....

Navigation

[0] Message Index

[#] Next page