Body Mount Coupler drilling Jig
( corrections were made to size of part F the correct size is now listed.)
and also a correction was made in reference to part C , Part F sits on top
of C and I mixed the two up , dislexic. sorry.
I will also repost a new sketch of my Jig.
PART-A make (1) 4" x6" x 3/4 " ---------pine
PART-B make (1) 3" x 4" x 1/8" ------- plexiglass
PART-C make (1) 1-1/2" x 7/8 " x 1/8" -plexiglass
PARTS -D + E make (2) 3/8" X 2-1/4" X 1/8"
PART - F make (1) 1-7/16" x 1-1/8" x 1/8"
you will need :
5/64" drill bit it should fit loosly in the bolster hole.
an old under carriage of a box car .
a 1/32" drill bit for drilling hole for mounting screws.
a tapping bit to cut threads in you under carriage.
a small quick clamp
super glue use sparingly.
I used a sanding block to rough up all surfaces of plexiglass to be glued.
Step 1- Drill 4 corner holes on part B using the 5/64" bit .
Then I also used a larger bit to counter sink the holes,
this will prevent the screw heads from cracking the plexiglass .
Square and center Part B on to part A. screw in place carefully.
Step 2 - Square part C 2-1/2" in onto part B and super glue
( this is the stop block where end of under carriage to be drilled will stop.)
Step 3-Square part D to part C super glue in place.
Step 4-Arrange your under carriage so the bottom is facing upwards and is tightly and squarely against Part D and butted up against Part C.
Clamp the under carriage in place , I also scribed a line along the side of under carriage that is showing
so I would know if anything had moved . So as to use the undercarriage to space parts D + E.
NOTE- keep clamp away from area for glueing part E. use super glue sparingly
Step 5- Super glue Part E in place. under carriage should be removed after these parts are glued and
has a chance to set if you are careful no glue will enter the channel.
Step 6- Drill a 5/64 " hole in part E and through part B but not into part A. secure
part E with a screw , remove clamp and repeat this step to part D.
Step 7- Now with an Exacto knife scrape any glue that may have entered the under carriage channel. a quick couple of scrapes should be all that is needed if you used glue sparingly.
Step 8- Replace the under carriage in the channel butt up against part C
then clamp in place.
Step 9- Use the 5/64" drill bit in a dremel tool and slowly drill through part B useing the bolster as a guide .Don't go too deep only through Part B.
Step 10-Now insert the screw in the bolster hole and secure it into part B it should be tight that is good , now remove the screw and carriage .
Step 11-please see new drawing of part F and remove the material specified , then Drill pilot holes in part F and C.
then Screw Part F to part C.
Again replace under carriage and screw .
Now make a tick mark in the center of part F close to the bolster hole .
score a square line across Part F exactly where the under carriage butts up against part C.
Now measure 3/16 " in from that line towards the bolster hole screw at the intersection of your tick marks, use a small center punch to gently make a dimple for your 1/32" drill bit to follow.
Slowly and squarely drill your plexiglass and under carriage.
Remove the bolster screw and switch carriage ends.
Replace the bolster screw this assures that the carriage does not move.
Drill the other end of the carriage with your 1/32" bit.
Step 12-When cutting the threads in the carriage do the opposite end of the carriage from where the bolster mount screw is , this will give you a free hand to turn the tapping bit .Do not use the tap bit in the drilling hole
in the plexiglas that would widen the hole .
Install your tapping bit into your dremel tool or micro hand drill (recommended) and turn the collet by hand slowly cutting the holes squarely in the under carriage.
Be careful not to wobble the holes in your under carriage, your screws will not fit correctly if this happens,
there is a remedy for this if it does happens.
Try to avoid this mistake.
Believe me I have done this , before I made this jig .
Repeat this on the other end of carriage. You are now ready to mount your couplers.
I also found it handy to use the spacer that comes in the kit
on the top side of carriage where screw pertrudes , I fasten it over the screw
line it up so it is even with the end then lightly super glue in place.
Your New Body Mount Coupler Drilling Jig can be clampted to you work bench or fastend with a few screws
you can also add a few holes in the pine to stand up your tools needed to do your work.
I believe I corrected the mistakes in the instructions and cut list. I sure hope I caught this in time , a new drawing is on it's way. thanks
Last edited by mrmartyman7 : 02-16-2011 at 03:50 PM.
Reason: add picture