OK, yet another pin routing thread. I figured I wouldn't hijack
woodworkers thread again.
So I had a chance to use my pin router this weekend, and it worked
great. I used it to make a relief for a house-number sign. It took
almost no time at all (carving the molds took some time, but once I
had those the sign itself was pretty fast). I switched out the router
bit at the end to a half-round to create some nice bevels, and used a
half-round chisel to distress the backdrop.
Check out the pics! ( http://www.ulvr.com/cgi-bin/yabb2/YaBB.pl?num=1283824903
)
That worked so well I decided to try it out for inlay, and that's
where I ran into issues. The problem was/is in creating a inverse
mold. I want to be able create accurate inverse molds quickly and
easily. So what I tried was plaster of paris. I created a shallow
dish, and poured the plaster around my original mold (OK, it was a
copy of my original mold, as I didn't want to wreck the original).
The hope was to remove the original, and have an absolute perfect
inverse. The problem was that the plaster of paris cracked when I was
lifting the original. I had sprayed my original with WD-40 before
trying this, but I don't think that was good enough. Does anyone have
any ideas on how to make this work? If I can get past this hurdle
then I should be able to do very accurate, and very nice looking
inlay, in very little time.
As far as the pin router goes, if anyone is interested, I created it
with MDF which is glued together (I tried putting some screws in, but
it seems that screws and MDF don't mix very well...). I used an arm
configuration as that would allow me to use bigger pieces. As you can
see from the pictures, it's simply clamped to the router table... No
bolts required. After playing with it, it seems that that's good
enough for what I was doing (cutting 1/4" cedar). It will shift if
you push it to hard though, but using the pin router doesn't seem to
do that. I have a detachable pin-holder, which holds either a 1/2"
or 1/4" pin. I can make another one if required. In the picture you
see the 1/2" pin. I cut the 1/2" bin a bit short so I tapped the end
and added a bolt, to give me a grip when raising/lowering the pin.
The pin can slide up or down if I loosen the wing nuts on the pin
holder. I have about 1/4mm play in any direction with a pound of
force, which I think is awesome. The whole thing took about an hour
plus glue-drying time to put together (but some of that time was spent
designing).
If I can figure out how to make inverse molds, I'm thinking of making
a bridge configuration for the pin router. That would likely have
even less play, and would not have the misalignment risks. But I
still need to figure out how to make the inverse molds.
John
In article
<d981578c-b840-450f-8044-e00b79acf22b@q40g2000prg.googlegroups.com>,
John <[email protected]> wrote:
> The problem was that the plaster of paris cracked when I was
> lifting the original. I had sprayed my original with WD-40 before
> trying this, but I don't think that was good enough.
Use vaseline. I'd also suggest some plaster impregnated gauze for the
first few layers around your original before pouring plaster.
On Sep 7, 6:05=A0pm, "Morgans" <[email protected]> wrote:
> "Dave Balderstone" <dave@N_O_T_T_H_I_Sbalderstone.ca> wrote in message
>
> news:070920101411013642%dave@N_O_T_T_H_I_Sbalderstone.ca...
>
> > In article
> > <d981578c-b840-450f-8044-e00b79acf...@q40g2000prg.googlegroups.com>,
> > John <[email protected]> wrote:
>
> >> The problem was that the plaster of paris cracked when I was
> >> lifting the original. =A0I had sprayed my original with WD-40 before
> >> trying this, but I don't think that was good enough.
>
> > Use vaseline. I'd also suggest some plaster impregnated gauze =A0for th=
e
> > first few layers around your original before pouring plaster.
>
> I am wondering if part of the problem is that the mold members need to ha=
ve
> some relief angle built into them.
>
> I wonder if you could use 1/2" bit, and do some grinding on it so that th=
e
> numbers and such have (perhaps) a 1/16" angle on the sides. =A0I think tr=
ying
> to pull straight sides out of a mold is asking a bit much of any lubrican=
t
> that you put on it.
>
> I really think that is the key, even though it would take a bit of work t=
o
> get to work right.
> --
> Jim in NC
Thanks for the suggestions. If possible, I'd like to avoid the relief
as it complicates the inlay (pin depth becomes more of a factor, as
does wear of the molds, etc). I will resort to it though if all else
fails.
I got a few more suggestions from friends. One that I found
interesting was that I was told was to drill small holes below the
mold to get rid of the vacuum effect when pulling the number up. I
was also told to use a thicker board that would not warp when I was
pulling the numbers up.
So... my next experiment will be: color the sides of the mold with
crayon, heat, and use a cloth to smooth, then add the Vaseline. Use a
thicker board that will not warp underneath. Let the Plaster of Paris
set for at least 24hrs. Drill a few small holes through the setup.
Be very, very careful when pulling the mold up.
I will try to avoid the relief angle but may resort to that later.
For the actual inlay I'm going to use a 17/32 pin and a 1/2" bit, so I
have just the tiniest bit of wiggle room. I'll try it this weekend
and let you know how it goes.
Wish me luck!
John
On Wed, 8 Sep 2010 07:38:07 -0700 (PDT), John wrote:
> On Sep 7, 6:05 pm, "Morgans" <[email protected]> wrote:
>> "Dave Balderstone" <dave@N_O_T_T_H_I_Sbalderstone.ca> wrote in message
>>
>> news:070920101411013642%dave@N_O_T_T_H_I_Sbalderstone.ca...
>>
>>> In article
>>> <d981578c-b840-450f-8044-e00b79acf...@q40g2000prg.googlegroups.com>,
>>> John <[email protected]> wrote:
>>
>>>> The problem was that the plaster of paris cracked when I was
>>>> lifting the original. I had sprayed my original with WD-40 before
>>>> trying this, but I don't think that was good enough.
>>
>>> Use vaseline. I'd also suggest some plaster impregnated gauze for the
>>> first few layers around your original before pouring plaster.
>>
>> I am wondering if part of the problem is that the mold members need to have
>> some relief angle built into them.
>>
>> I wonder if you could use 1/2" bit, and do some grinding on it so that the
>> numbers and such have (perhaps) a 1/16" angle on the sides. I think trying
>> to pull straight sides out of a mold is asking a bit much of any lubricant
>> that you put on it.
>>
>> I really think that is the key, even though it would take a bit of work to
>> get to work right.
>> --
>> Jim in NC
>
>
> Thanks for the suggestions. If possible, I'd like to avoid the relief
> as it complicates the inlay (pin depth becomes more of a factor, as
> does wear of the molds, etc). I will resort to it though if all else
> fails.
>
> I got a few more suggestions from friends. One that I found
> interesting was that I was told was to drill small holes below the
> mold to get rid of the vacuum effect when pulling the number up. I
> was also told to use a thicker board that would not warp when I was
> pulling the numbers up.
>
> So... my next experiment will be: color the sides of the mold with
> crayon, heat, and use a cloth to smooth, then add the Vaseline. Use a
> thicker board that will not warp underneath. Let the Plaster of Paris
> set for at least 24hrs. Drill a few small holes through the setup.
> Be very, very careful when pulling the mold up.
>
> I will try to avoid the relief angle but may resort to that later.
> For the actual inlay I'm going to use a 17/32 pin and a 1/2" bit, so I
> have just the tiniest bit of wiggle room. I'll try it this weekend
> and let you know how it goes.
>
> Wish me luck!
>
> John
Use the vaseline like someone mentioned and in place of plaster
use bondo, will withstand much more abuse getting it free.
basilisk
"Dave Balderstone" <dave@N_O_T_T_H_I_Sbalderstone.ca> wrote in message
news:070920101411013642%dave@N_O_T_T_H_I_Sbalderstone.ca...
> In article
> <d981578c-b840-450f-8044-e00b79acf22b@q40g2000prg.googlegroups.com>,
> John <[email protected]> wrote:
>
>> The problem was that the plaster of paris cracked when I was
>> lifting the original. I had sprayed my original with WD-40 before
>> trying this, but I don't think that was good enough.
>
> Use vaseline. I'd also suggest some plaster impregnated gauze for the
> first few layers around your original before pouring plaster.
I am wondering if part of the problem is that the mold members need to have
some relief angle built into them.
I wonder if you could use 1/2" bit, and do some grinding on it so that the
numbers and such have (perhaps) a 1/16" angle on the sides. I think trying
to pull straight sides out of a mold is asking a bit much of any lubricant
that you put on it.
I really think that is the key, even though it would take a bit of work to
get to work right.
--
Jim in NC
"John" <[email protected]> wrote
So... my next experiment will be: color the sides of the mold with
crayon, heat, and use a cloth to smooth, then add the Vaseline. Use a
thicker board that will not warp underneath. Let the Plaster of Paris
set for at least 24hrs. Drill a few small holes through the setup.
Be very, very careful when pulling the mold up.
I will try to avoid the relief angle but may resort to that later.
For the actual inlay I'm going to use a 17/32 pin and a 1/2" bit, so I
have just the tiniest bit of wiggle room. I'll try it this weekend
and let you know how it goes.
Wish me luck!
******************************************
Another think I just remembered from pulling fiberglass parts. Use those
holes to put a few blasts of compressed air between the mold and casting.
That can really help to break them apart!
--
Jim in NC
On Wed, 8 Sep 2010 09:40:02 -0700, Lew Hodgett wrote:
> "basilisk" wrote:
>> Use the vaseline like someone mentioned and in place of plaster
>> use bondo, will withstand much more abuse getting it free.
> ----------------------------
> If you use Bondo, use mold release available from any fiberglass
> supplier.
>
> Lew
Good point, and another- if bondo is too thick, you can thin it with
polyester resin or just use the resin by itself.
basilisk