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Grinder
in a box!
A
while ago, a grinder kit came on the market. Things
happened, and it was no longer available. Then, Chris (aka
blindhogg at Bladeforums) redrew a similar design. The cad
files can be found at http://blindhogg.com/eerfgrinder.html
A number of people have been kind enough to share pictures of their completed grinder.
We talked a bit, made a few changes, and this is what came of it.
I'll be offering this grinder kit for $250 plus shipping
($10.20 in the US via USPS flat rate box.) I can only make it
to
the post office to ship these on Fridays. I'll have everything
boxed up and ready to ship each week. When ordering, please include
which platen style you'd prefer (pictured below). I accept credit cards
only at this point(not paypal, though).
If you want to use a MAP arm it will not work with the
current design of this kit. As the kit progresses, there may
be a way to use them together.
There is a hardware/tool list at the bottom of this page.
This grinder is designed to use a motor with a 56c frame.
First, here's what is included in the kit:
The kit also comes with choice of platen, standard or multi.
The standard platen is designed to use 2 or 3 inch wheels
with the platen inbetween. It has an adjustment to tilt it
forward or back. The multi platen is designed to have a 2 or
3 inche wheel at the top, and a 5, 6, or 8 inch wheel at the bottom
with the platen inbetween.
Here's what the multi platen looks like without the actual platen
attached. You can rotate to any of the wheels or work areas, or
any angle inbetween.
And
a setup for the standard platen. This is on my grinder, and is
the old style before I added the angle adjustment. There is a
piece of angle with slots cut in it for adjustment that the actual
platen attaches to. I usually use a hardened piece of A2, but in
this picture it's a piece of mild steel. I haven't made a new one
for this grinder yet.
With the exception of the three shims (cut from 16g mild steel) the
remaining pieces are laser cut from 1/2 steel. All
that is needed to fnish it, is drill a few holes, tap a few holes, and
countersink a few holes. After that, add a motor, a few
wheels and a tooling bar, and you've got a grinder!
Here's what the finished grinder looks like.
The motor and bolts are NOT
included in the this kit, but are shown for
demonstration purposes. The openings are 1 1/2"
square for the tooling arm and for the work rest. If you
choose not to use a workrest, then the bottom few pieces don't need to
be attached.
This is how I assemble it. There is more than one way to do
this, so if you end up going in a different order or doing things a
little different, it's the end result that matters.
First, I attach the upright to the base. The main upright has
a tab to fit into a slot in the base.
The image on the left shows the assembly (upside down) with the base
sitting in it's slot. Notice that it's not square.
If you transfer the holes now, they won't line up very well.
Clamping a piece of angle iron to keep things square works
nicely. The right angle magnetic welders magnets will work
for this as well.
Next, use the holes in the base to transfer the hole locations.
I often use a drill bit to do this. I just use a
bit that barely fits through the hole, and drill just enough to create
a spot mark. You can also use a punch.
Here's what the marks look like when using the drill method.
Next, dril the holes for 1/4 - 20 threads, I use a #6 drill bit (.204
inches ). After drilling the holes deeper than you want to
tap, then I countersink each hole. It helps start the tap and
it prevents a fat thread from sticking above the surface.
Make sure to use a lubricant when tapping. If you
feel excessive pressure, stop tapping, remove the tap and clear the
threads. Broken taps are not fun to deal with.
Note, I'm using an angle plate to hole the upright, if you don't have
one, angle iron will work.
After tapping the holes, I countersink the bottom of the baseplate.
I countersink it deep enough so that the head of the bolt is below the
level of the plate. If you plan on using socket head cap
screws, you could also counterbore this hole instead.
Now if you want to bypass the drilling/tapping routine of the base
plate to the upright, you can weld it, too.
While you're setup for countersinking and tapping, I countersink both
sides of the following holes(circled in red) and then tap them with 1/4
- 20 as well.
Next, I clamp these piece together and go through the same steps that I
did for the main upright and the base. Transfer the hole
location, drill, countersink, and tap 1/4 - 20.
I remember building models as a kid where everything was on one sheet,
and you removed the parts as you need them. The part in the
image above came from this tree of parts. The six pieces are
spacers, and the rectangular block is next.
It gets tapped with 1/2 - 13. Remember to countersink the
hole first and use lubrication.
Since this piece is the pivot for the tensioner/idler, it needs a cross
hole drill into it. I use a punch to locate the hole
approximately a 1/4" in from the end and centered. Note that
I have this setup in a vice. DO NOT try to hold this with
your hand.
Same thing happens with the support piece.
You can do this part one of two ways.
The one on the left was drill through with a .204 drill bit, and then
only the left segment was drilled for clearance for the bolt.
The left side was then tapped. The one on the right
was drill with clearance the hole way through and then a nut was used.
Either way works.
Here's how the spring attaches. The location will vary
depending on the spring. The eye bolt is bolted into a 1/4 -
20 hole in the main upright.
The handle has a couple options. I tapped it with 1/2 - 13
and just tightened in bolt. You can also use it as a
clearance hole for a 3/8 inch bolt.
Here's what it looks like with a mockup for a 72" inch belt and the
standard platen. I run 90" belts, and shortened one for
demonstration purposes. (It will look out of proportion for
those that run 72" belts if I had a 90 on it.) I'll be
borrowing some 72" belts to show what it looks like fully assembled.
This also has the old style of standard platen. The
new one includes angle adjustment.
With the standard platen, you can run 60" belts,
all the way up to 90" belts,
I'll take more updated pictures a little bit later.
Here's a list of the tooling that I used:
#6 drill bit, .204
clearance for 1/4 bolts (I used 17/64 for my build)
punch
counter sink, small and large
1/4 - 20 tap
1/2 - 13 tap
oil
angle iron and clamps
vise
handles for taps
Here's the hardware I used:
(4) 3/8 - 16 bolts x 1 inch (attaching motor to upright)
(4-6) 1/4 - 20 bolts x 1/2 inch (attaching motor to base)
(4) 1/4 - 20 bolts x 3/4 inch (attaching base to main
upright)
(8) 1/4 - 20 bolts x 3 inches (tooling arm and workest
support)
(4) 1/4 - 20 bolts x 3 1/2 inches (tooling arm and workest
support)
(2) 1/4 - 20 bolts x 1 inch (idler wheel support)
(1) 1/4 - 20 bolt x 3 inches (idler wheel support
pivot)
(3) 1/4 - 20 bolts for idler adjustment and tooling
arm/workrest support
(3) 3/8 - 16 bolts x 2 1/2 inches (idler upright to main
upright)
(1) 1/2 - 13 bolt x 1 1/2 inches (idler upright to idler arm)
All
the wheels in the platen and idler arm are meant to be mounted on a
1/2 inch bolt. If you use something different, you may have
to adjust the hole size. A good source for wheels is www.usaknifemaker.com
You
can get smaller wheels, idler wheels, contact wheels, larger wheels
as well as belts there.
Here's
an estimated parts break down for a standard platen:
Grinder
kit - $250 (plus $10.20 shipping)
Motor
(locally I got a 1 1/2 hp) $225
Drive
wheel -
$53
Contact
wheel (assuming 2 for standard platen @ $44 apiece) - $88
Idler/tensioner
wheel -
$58
Misc hardware (estimate, I had most of this already) - $25
Total = $709.20
The motor price and misc hardware will change this the most.
Here's
an estimated parts break down for a multi platen:
Grinder kit - $250 (plus $10.20 shipping)
Motor (locally I got a 1 1/2 hp) $225
Drive
wheel - $53
Contact
wheel - $44
Idler/tensioner
wheel - $58
8"
contact wheel - $98
Misc hardware (estimate, I had most of this already) - $25
Total = $763.20
The motor price and misc hardware will change this the most.
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