Greetings All,
I have a customer who brought me some aluminum castings to repair that
required welding. After welding up several deep gouges and grinding
the welds flush the repaired surface doesn't resemble the original
cast surface. The customer knew this would happen but would like it if
I could make the repairs look like the original casting. I have tried
glass bead and walnut shells but the finish is still too fine. At the
same time the finish is also absorbent. So the glass beads are too
sharp.The original cast surface shows clearly that the parts were sand
castings and I'm wondering if steel shot or bead media might be the
best to use to copy the surface. I will be blasting the complete
surface of the parts to help disguise the repairs. So, can anybody
point me in the right direction?
Thanks,
Eric

wrote in message
...
Greetings All,
I have a customer who brought me some aluminum castings to repair that
required welding. After welding up several deep gouges and grinding
the welds flush the repaired surface doesn't resemble the original
cast surface. The customer knew this would happen but would like it if
I could make the repairs look like the original casting. I have tried
glass bead and walnut shells but the finish is still too fine. At the
same time the finish is also absorbent. So the glass beads are too
sharp.The original cast surface shows clearly that the parts were sand
castings and I'm wondering if steel shot or bead media might be the
best to use to copy the surface. I will be blasting the complete
surface of the parts to help disguise the repairs. So, can anybody
point me in the right direction?
Thanks,
Eric

I was able to mimic the texture in cast iron with a needle scaler. It was a
long time ago and I don't recall anything special about the repair except I
used pretty low air pressure.
Steve

wrote:
Greetings All,
I have a customer who brought me some aluminum castings to repair that
required welding. After welding up several deep gouges and grinding
the welds flush the repaired surface doesn't resemble the original
cast surface. The customer knew this would happen but would like it if
I could make the repairs look like the original casting. I have tried
glass bead and walnut shells but the finish is still too fine. At the
same time the finish is also absorbent. So the glass beads are too
sharp.The original cast surface shows clearly that the parts were sand
castings and I'm wondering if steel shot or bead media might be the
best to use to copy the surface. I will be blasting the complete
surface of the parts to help disguise the repairs. So, can anybody
point me in the right direction?
Thanks,
Eric

Try low pressure (30-40psi) and coal slag 60-120 grit, just flash the
surface and it should darken a bit. Coal slag cuts aluminum FAST.

Matt

On Wed, 26 Nov 2008 15:36:40 -0600, "Up North"
wrote:


wrote in message
...
Greetings All,
I have a customer who brought me some aluminum castings to repair that
required welding. After welding up several deep gouges and grinding
the welds flush the repaired surface doesn't resemble the original
cast surface. The customer knew this would happen but would like it if
I could make the repairs look like the original casting. I have tried
glass bead and walnut shells but the finish is still too fine. At the
same time the finish is also absorbent. So the glass beads are too
sharp.The original cast surface shows clearly that the parts were sand
castings and I'm wondering if steel shot or bead media might be the
best to use to copy the surface. I will be blasting the complete
surface of the parts to help disguise the repairs. So, can anybody
point me in the right direction?
Thanks,
Eric

I was able to mimic the texture in cast iron with a needle scaler. It was a
long time ago and I don't recall anything special about the repair except I
used pretty low air pressure.
Steve


Thanks Steve. My neighbor has one of those. I'll give it a try.
Eric

"matthew maguire" wrote in message
...
wrote:
Greetings All,
I have a customer who brought me some aluminum castings to repair that
required welding. After welding up several deep gouges and grinding
the welds flush the repaired surface doesn't resemble the original
cast surface. The customer knew this would happen but would like it if
I could make the repairs look like the original casting. I have tried
glass bead and walnut shells but the finish is still too fine. At the
same time the finish is also absorbent. So the glass beads are too
sharp.The original cast surface shows clearly that the parts were sand
castings and I'm wondering if steel shot or bead media might be the
best to use to copy the surface. I will be blasting the complete
surface of the parts to help disguise the repairs. So, can anybody
point me in the right direction?
Thanks,
Eric

Try low pressure (30-40psi) and coal slag 60-120 grit, just flash the
surface and it should darken a bit. Coal slag cuts aluminum FAST.

Matt

That's the problem he's having now from all indications. He commented on
the porous surface.

No cutting action is desired for this operation, just blending of existing
surfaces. Peening is adequate

If the proper size of glass bead is coupled with the proper air pressure,
there will be no cutting. Glass bead peens, but if it becomes fractured,
it begins to cut. It's obvious when it does, for it changes appearance.
Glass beads in good condition are a glossy off white color. As they begin
to break down, they shift to a more white color, more opaque, and they begin
cutting, and yielding considerable dust. Glass bead that is functioning
properly yields no dusting.

Harold

Harold and Susan Vordos wrote:

Try low pressure (30-40psi) and coal slag 60-120 grit, just flash the
surface and it should darken a bit. Coal slag cuts aluminum FAST.

Matt

That's the problem he's having now from all indications. He commented on
the porous surface.

No cutting action is desired for this operation, just blending of existing
surfaces. Peening is adequate

If the proper size of glass bead is coupled with the proper air pressure,
there will be no cutting. Glass bead peens, but if it becomes fractured,
it begins to cut. It's obvious when it does, for it changes appearance.
Glass beads in good condition are a glossy off white color. As they begin
to break down, they shift to a more white color, more opaque, and they begin
cutting, and yielding considerable dust. Glass bead that is functioning
properly yields no dusting.

Harold



Yup, I haven't tried to blend cast/weld aluminum that I can remember,
just thought the sharp pitting caused by black beauty might approximate
a cast surface, and I have used it with stainless and it seemed to
change things to a more uniform dull grey color, with hot work tool
steel you have a tough time telling I've been there.

Don't use the beads anymore, most of my abrasive work is de-scale or
de-oxidize, dry-hone or really peen. For these things I use coal slag,
granite, stainless grit and steel shot.

It was just a thought... but after reading the other post, a needle
scaler at a sharp angle should work well also.

Matt

On Thu, 27 Nov 2008 05:08:24 -0600, matthew maguire
wrote:

wrote:
Greetings All,
I have a customer who brought me some aluminum castings to repair that
required welding. After welding up several deep gouges and grinding
the welds flush the repaired surface doesn't resemble the original
cast surface. The customer knew this would happen but would like it if
I could make the repairs look like the original casting. I have tried
glass bead and walnut shells but the finish is still too fine. At the
same time the finish is also absorbent. So the glass beads are too
sharp.The original cast surface shows clearly that the parts were sand
castings and I'm wondering if steel shot or bead media might be the
best to use to copy the surface. I will be blasting the complete
surface of the parts to help disguise the repairs. So, can anybody
point me in the right direction?
Thanks,
Eric

Try low pressure (30-40psi) and coal slag 60-120 grit, just flash the
surface and it should darken a bit. Coal slag cuts aluminum FAST.

Matt
Greetings Matt,
What I'm trying to do is peen the surface. I don't want to cut the
surface. You mentioned coal slag and I've never heard of it. I do use
a black abrasive sometimes that is really sharp and cuts fast. I
wonder if it is coal slag.
Thanks,
Eric

On Fri, 28 Nov 2008 01:42:24 GMT, "Harold and Susan Vordos"
wrote:


"matthew maguire" wrote in message
...
wrote:
Greetings All,
I have a customer who brought me some aluminum castings to repair that
required welding. After welding up several deep gouges and grinding
the welds flush the repaired surface doesn't resemble the original
cast surface. The customer knew this would happen but would like it if
I could make the repairs look like the original casting. I have tried
glass bead and walnut shells but the finish is still too fine. At the
same time the finish is also absorbent. So the glass beads are too
sharp.The original cast surface shows clearly that the parts were sand
castings and I'm wondering if steel shot or bead media might be the
best to use to copy the surface. I will be blasting the complete
surface of the parts to help disguise the repairs. So, can anybody
point me in the right direction?
Thanks,
Eric

Try low pressure (30-40psi) and coal slag 60-120 grit, just flash the
surface and it should darken a bit. Coal slag cuts aluminum FAST.

Matt

That's the problem he's having now from all indications. He commented on
the porous surface.

No cutting action is desired for this operation, just blending of existing
surfaces. Peening is adequate

If the proper size of glass bead is coupled with the proper air pressure,
there will be no cutting. Glass bead peens, but if it becomes fractured,
it begins to cut. It's obvious when it does, for it changes appearance.
Glass beads in good condition are a glossy off white color. As they begin
to break down, they shift to a more white color, more opaque, and they begin
cutting, and yielding considerable dust. Glass bead that is functioning
properly yields no dusting.

Harold


Greetings Harold,
The glass bead I'm using now is so fine it almost flows like water.
Maybe I need to switch to a larger size. I will try lowering the
pressure too. Could be it's cutting because the pressure is too high
and the bead is breaking up. There has been no color change though.
Thanks,
Eric

wrote:
On Fri, 28 Nov 2008 01:42:24 GMT, "Harold and Susan Vordos"
wrote:

"matthew maguire" wrote in message
...
wrote:
Greetings All,
I have a customer who brought me some aluminum castings to repair that
required welding. After welding up several deep gouges and grinding
the welds flush the repaired surface doesn't resemble the original
cast surface. The customer knew this would happen but would like it if
I could make the repairs look like the original casting. I have tried
glass bead and walnut shells but the finish is still too fine. At the
same time the finish is also absorbent. So the glass beads are too
sharp.The original cast surface shows clearly that the parts were sand
castings and I'm wondering if steel shot or bead media might be the
best to use to copy the surface. I will be blasting the complete
surface of the parts to help disguise the repairs. So, can anybody
point me in the right direction?
Thanks,
Eric
Try low pressure (30-40psi) and coal slag 60-120 grit, just flash the
surface and it should darken a bit. Coal slag cuts aluminum FAST.

Matt
That's the problem he's having now from all indications. He commented on
the porous surface.

No cutting action is desired for this operation, just blending of existing
surfaces. Peening is adequate

If the proper size of glass bead is coupled with the proper air pressure,
there will be no cutting. Glass bead peens, but if it becomes fractured,
it begins to cut. It's obvious when it does, for it changes appearance.
Glass beads in good condition are a glossy off white color. As they begin
to break down, they shift to a more white color, more opaque, and they begin
cutting, and yielding considerable dust. Glass bead that is functioning
properly yields no dusting.

Harold


Greetings Harold,
The glass bead I'm using now is so fine it almost flows like water.
Maybe I need to switch to a larger size. I will try lowering the
pressure too. Could be it's cutting because the pressure is too high
and the bead is breaking up. There has been no color change though.
Thanks,
Eric

I just used GunKote on a pistol. For prep I expected to glass bead it.
In the instructions for the GunKote produ ct, it recommended roughening
the surface by sand blasting and a few other means. It specifically said
NOT to bead blast, because it peens the surface and closes the pores.
I found that a bit unusual.

BTW, I wend ahead and glass beaded it. The resultant surface certainly
looked rough, and not peened.