Original Posted By: del magsam
Just sent my rant about airfoils, caught three misspellings after the fact,I hate that.To all those who are building a Corvair engine, it's been suggested thatabrasive blasting with walnuts shells is a great way to get the surfacesclean and bright. As I have a sandblaster, I started looking for a supplierof walnut shells. Eastwood (automotive products, etc.) had a 50lb bag for$45 plus $30 shipping, I about choked. That seemed to be the same price forall the traditional suppliers. Fortunately, I found a food producer thatsells walnut products and sells the walnut shells, ground to severaldifferent sieves, as a byproduct. They are Hammons(http://www.black-walnuts.com/) out of Missouri and the 50lb bag was $15plus about that for shipping. They took a phone order by credit card, andthe bag arrived four days later.I had to explain to the wife when she saw the receipt what the heck I needed50lbs of walnut shells for.Robert HainesDu Quoin, Illinois________________________________________________________________________________Date: Mon, 2 Feb 2004 08:04:47 -0800 (PST)
Pietenpol-List: walnut shells and airfoil talk
Re: Pietenpol-List: walnut shells and airfoil talk
Original Posted By: "Robert Haines"
If you use industrial grade baking soda, it does a good job and is watersoluable so that you rinse the engine out with water when you are done andall the abrasive is gone.Chris Bobka----- Original Message -----
If you use industrial grade baking soda, it does a good job and is watersoluable so that you rinse the engine out with water when you are done andall the abrasive is gone.Chris Bobka----- Original Message -----
Pietenpol-List: walnut shells and airfoil talk
Original Posted By: del magsam
Re: Pietenpol-List: walnut shells and airfoil talk
Original Posted By: del magsam
Del,Try this website for info:http://www.transportandconstruction.co.za/rasmech.htmlI know, I know they are in New Zealand. But there was a guy in Winona marketingthis stuff at Oshkosh about ten years ago. His name is Mike Thern. I thinkhe was a teacher in the aviation tech school down at the winona airport. I wouldcontact him at the airport at 507 864 2705 or at home at 507 454 2705 andask him where it can be had. These phone numbers a current as I just got theinfo from the Luscombe association newsletter that came in saturday's mail. I know the soda is cheap. He may be out of the business becuase it is so easyto purchase hence everybody bought it elsewhere. Please let the piet list knowwhat you find out.chris bobka ----- Original Message -----
Del,Try this website for info:http://www.transportandconstruction.co.za/rasmech.htmlI know, I know they are in New Zealand. But there was a guy in Winona marketingthis stuff at Oshkosh about ten years ago. His name is Mike Thern. I thinkhe was a teacher in the aviation tech school down at the winona airport. I wouldcontact him at the airport at 507 864 2705 or at home at 507 454 2705 andask him where it can be had. These phone numbers a current as I just got theinfo from the Luscombe association newsletter that came in saturday's mail. I know the soda is cheap. He may be out of the business becuase it is so easyto purchase hence everybody bought it elsewhere. Please let the piet list knowwhat you find out.chris bobka ----- Original Message -----
Pietenpol-List: Re: walnut shells and airfoil talk
Original Posted By: MacklemAW(at)aol.com
I've got no experience here, but I chose the 20/30 (they mentioned it wasone of the more popular grades), it appeared to be middle of the line mediumabrasive. Now that I have it, it has the size of coarse sand, just forcomparison, but I'm sure walnut shell sieve and sand sieve do not correspondas far as fine/medium/coarse grading. I haven't used it yet, I can'tcomment yet.Also, baking soda, I've read somewhere at sometime and may or may not beright (how's that for a disclaimer?) attacks aluminum. Again, I don't knowfor sure. Although, I do know that walnut shells pose no chemical danger.:)I do have a copy of the CORSA magazine that has the proceedings from a CORSApresentation that the plant manager of the engine factory gave (November1997?). It was interesting but I wished there was more technical details onhow they did what they did. He mentioned that the heads and cases were lowpressure die cast with sand cores. They had problems getting the core sandout of the heads until they figured out about abrasive blasting with walnutshells, and so that's how they were cleaned at the factory. He mentionedthat they bought walnut shells by the rail car load. So, if it's goodenough for the guys who built them in the first place, it'll be OK with me.Robert HainesDu Quoin, Illinois________________________________________________________________________________
I've got no experience here, but I chose the 20/30 (they mentioned it wasone of the more popular grades), it appeared to be middle of the line mediumabrasive. Now that I have it, it has the size of coarse sand, just forcomparison, but I'm sure walnut shell sieve and sand sieve do not correspondas far as fine/medium/coarse grading. I haven't used it yet, I can'tcomment yet.Also, baking soda, I've read somewhere at sometime and may or may not beright (how's that for a disclaimer?) attacks aluminum. Again, I don't knowfor sure. Although, I do know that walnut shells pose no chemical danger.:)I do have a copy of the CORSA magazine that has the proceedings from a CORSApresentation that the plant manager of the engine factory gave (November1997?). It was interesting but I wished there was more technical details onhow they did what they did. He mentioned that the heads and cases were lowpressure die cast with sand cores. They had problems getting the core sandout of the heads until they figured out about abrasive blasting with walnutshells, and so that's how they were cleaned at the factory. He mentionedthat they bought walnut shells by the rail car load. So, if it's goodenough for the guys who built them in the first place, it'll be OK with me.Robert HainesDu Quoin, Illinois________________________________________________________________________________
Re: Pietenpol-List: walnut shells and airfoil talk
Original Posted By: "Christian Bobka"
What is the difference between baking soda and industrial grade BS? Morefor a cheaper per pound price?----- Original Message -----
What is the difference between baking soda and industrial grade BS? Morefor a cheaper per pound price?----- Original Message -----
Re: Pietenpol-List: walnut shells and airfoil talk
Original Posted By: "Robert Haines"
What grit size did you buy?----- Original Message -----
What grit size did you buy?----- Original Message -----
Pietenpol-List: Re: walnut shells and airfoil talk
Original Posted By: "Larry Ragan"
Industrial grade BS?! (oh, you meant baking soda...)RH________________________________________________________________________________
Industrial grade BS?! (oh, you meant baking soda...)RH________________________________________________________________________________
RE: Pietenpol-List: walnut shells and airfoil talk
Original Posted By: "Robert Haines"
I think if you were to use regular baking soda (sodium bicarbonate)you could purchase it through swimming pool suppliers. It is used tobalance ph and can be purchased in 50# bags. Don't buy it at the localpool supplier because they repackage it in 5#containers....rename it....and jackthe price up.Larry Ragan Jacksonville, Fl. lragan(at)hotmail.com ________________________________________________________________________________
I think if you were to use regular baking soda (sodium bicarbonate)you could purchase it through swimming pool suppliers. It is used tobalance ph and can be purchased in 50# bags. Don't buy it at the localpool supplier because they repackage it in 5#containers....rename it....and jackthe price up.Larry Ragan Jacksonville, Fl. lragan(at)hotmail.com ________________________________________________________________________________
Pietenpol-List: Re: walnut shells and airfoil talk
Original Posted By: "Deon Engelmann"
Apparently I didn't do a good job making my point. What I meant to say wasthat walnut shells at 20 sieve (U.S. Mesh at approximately 0.030" indiameter so says Hammons) and sand at 20 sieve may not be considered in thesame abrasive category; where a 20 sieve sand is considered "coarse" (I'mpretty sure about that), 20 sieve walnut shell may be considered "medium"(or "coarse" or "fine"). I'm not sure of this gradation, but this is thepoint I was trying to make. They could be graded exactly the same, I justdidn't want to assume this to be true considering they are somewhatdifferent materials.What I want is a "medium" walnut shell abrasive since my parts are notcovered with mud, crud, paint, rust, etc. Also, most abrasives get smallerwith use, so eventually (no telling how long) I would likely end up with"fine" anyway. Since Hammons, in their FAQ section, noted that 8/12, 12/20,and 20/30 were their most popular, and my assumption was most applicationsuse "coarse" and "medium", I concluded that 20/30 was probably "medium".Just a guess.Robert HainesDu Quoin, Illinois________________________________________________________________________________
Apparently I didn't do a good job making my point. What I meant to say wasthat walnut shells at 20 sieve (U.S. Mesh at approximately 0.030" indiameter so says Hammons) and sand at 20 sieve may not be considered in thesame abrasive category; where a 20 sieve sand is considered "coarse" (I'mpretty sure about that), 20 sieve walnut shell may be considered "medium"(or "coarse" or "fine"). I'm not sure of this gradation, but this is thepoint I was trying to make. They could be graded exactly the same, I justdidn't want to assume this to be true considering they are somewhatdifferent materials.What I want is a "medium" walnut shell abrasive since my parts are notcovered with mud, crud, paint, rust, etc. Also, most abrasives get smallerwith use, so eventually (no telling how long) I would likely end up with"fine" anyway. Since Hammons, in their FAQ section, noted that 8/12, 12/20,and 20/30 were their most popular, and my assumption was most applicationsuse "coarse" and "medium", I concluded that 20/30 was probably "medium".Just a guess.Robert HainesDu Quoin, Illinois________________________________________________________________________________
RE: Pietenpol-List: walnut shells and airfoil talk
Original Posted By: owner-pietenpol-list-server(at)matronics.com
HiThis company is actually in Alrode, Johannesburg, South Africa (.co.za).It is about 25 min from where I stay.Deon EngelmannEAA322 Midrand # SA12055PretoriaSouth Africa-----Original Message-----
HiThis company is actually in Alrode, Johannesburg, South Africa (.co.za).It is about 25 min from where I stay.Deon EngelmannEAA322 Midrand # SA12055PretoriaSouth Africa-----Original Message-----
Re: Pietenpol-List: walnut shells and airfoil talk
Original Posted By: "Robert Haines"
In my line of work, over the years, when we wanted less destructive blastingwe always used ground corn cob. It comes in the consistisy of cornmeal but it's the cob. Think places like Grainger or McMaster Carr stocksit.walt evansNX140DL----- Original Message -----
In my line of work, over the years, when we wanted less destructive blastingwe always used ground corn cob. It comes in the consistisy of cornmeal but it's the cob. Think places like Grainger or McMaster Carr stocksit.walt evansNX140DL----- Original Message -----
Pietenpol-List: Re: walnut shells and airfoil talk
Original Posted By: "walt evans"
My Granger catalog only had glass bead. However, my McMaster-Carr cataloghad a number of choices, including walnut shells and corn cob. Walnut shellwas $25.00 for 50lb at 20/30 (the cheapest) and cob at $18.35 for 50lb at20/40 (also the cheapest). The heavier grit get slightly more expensive.Shipping is not known.Thus, my recommendation for Hammons at $15.00 per 50lb bag of walnut shell.Frustrating thing is that I'm in the middle of corn cob country. You wouldthink that I could get all I wanted for free if I was willing to pickthrough the fields in the Fall and grind it myself. :)Walt - what were you using cob blasting for and what were your experiences?Robert HainesDu Quoin (located between this corn field and that one), Illinois________________________________________________________________________________
My Granger catalog only had glass bead. However, my McMaster-Carr cataloghad a number of choices, including walnut shells and corn cob. Walnut shellwas $25.00 for 50lb at 20/30 (the cheapest) and cob at $18.35 for 50lb at20/40 (also the cheapest). The heavier grit get slightly more expensive.Shipping is not known.Thus, my recommendation for Hammons at $15.00 per 50lb bag of walnut shell.Frustrating thing is that I'm in the middle of corn cob country. You wouldthink that I could get all I wanted for free if I was willing to pickthrough the fields in the Fall and grind it myself. :)Walt - what were you using cob blasting for and what were your experiences?Robert HainesDu Quoin (located between this corn field and that one), Illinois________________________________________________________________________________
Re: Pietenpol-List: Re: walnut shells and airfoil talk
Original Posted By: "Robert Haines"
Robert,I didn't personly use it, but in talking with our engineering P.E. (who hassince left and is with EASA) The sand grit actually hits and leaves a "barb"since the sand is much harder that the steel/alum. And it could short outthe laminations on an AC motor. Where the corn cob is softer and eitherdoesn't touch/flattens the surface on the steel. {{We are one of thelargest electric motor/pump facilities in the northeast (only one ISO 9001certified first time out)}}But actually now they've switched to using a high pressure water blasterthat can also add backing soda to the mix for action. (the one where theoperator wears "tim man" shin and foot covers to limit cutting off toes.)Don't know where cob, walnut shells, and baking soda compare, but justwanted to bring up another option. I imagine that if baking soda does the job ( and since it's not an acid,buta base?) Like Chris Bobka suggested, it's probably the best way to go.Besides, when you're done, you can make buscuits. :)walt evansNX140DL----- Original Message -----
Robert,I didn't personly use it, but in talking with our engineering P.E. (who hassince left and is with EASA) The sand grit actually hits and leaves a "barb"since the sand is much harder that the steel/alum. And it could short outthe laminations on an AC motor. Where the corn cob is softer and eitherdoesn't touch/flattens the surface on the steel. {{We are one of thelargest electric motor/pump facilities in the northeast (only one ISO 9001certified first time out)}}But actually now they've switched to using a high pressure water blasterthat can also add backing soda to the mix for action. (the one where theoperator wears "tim man" shin and foot covers to limit cutting off toes.)Don't know where cob, walnut shells, and baking soda compare, but justwanted to bring up another option. I imagine that if baking soda does the job ( and since it's not an acid,buta base?) Like Chris Bobka suggested, it's probably the best way to go.Besides, when you're done, you can make buscuits. :)walt evansNX140DL----- Original Message -----
Pietenpol-List: Re: walnut shells and airfoil talk
Original Posted By:> "walt evans"
Wet abrasive blasting, sounds effective but messy. :)Yes, baking soda is alkaline (a base) and from what I've read (again, noexperience here so don't consider this gospel) baking soda discolors thealuminum like an acid, etch cleaner, or oven cleaner would. I don't thinkthis would cause any structural or surface damage, only cosmetic. Also,William Wynne pointed out in his conversion manual that sand blasting andbead blasting does what you mentioned in your previous post, and the changeto the surface screws up things like the lifter bores. He noted thatcleaners and pressure washing was the way to go and the truth about that isthat it cleans with no abrasion. If you only need to get the dirt off, thisis preferable.Although, some of us also want a little corosion removal and to provide alittle polishing action, this is not possible with pressure washing alone.At that point, it appears to me that you have two options, one is tomechanically polish with a small metal brush or a buffing wheel in a rotarytool, and the second is a light abrasive blast. The metal brush is similarto sand blasting in that it deforms the surface, which is no big deal to thelifter bores (etc.) because you would never get the brush in there anyway.The only other problems I have with the metal brush is that, one, it imbedsthe aluminum oxide formed on the surface down into the surface a littlewhich may cause problems with welding (but if you don't plan of welding, nobig deal) and, two, it takes a lot of work.Again, this is only my opinion and the thought process I used to get me tothe decision on walnut shell blasting. I would like to note that DJ, who isdoing an excellent job on his project, cleaned with oven cleaner and apressure washer and then wire brushed and otherwise polished his engine. Healso then welded the intake runners on. So I may be a little overboard inmy thinking since it can be done satisfactorily to the contrary.Robert HainesDu Quoin, Illinois
Wet abrasive blasting, sounds effective but messy. :)Yes, baking soda is alkaline (a base) and from what I've read (again, noexperience here so don't consider this gospel) baking soda discolors thealuminum like an acid, etch cleaner, or oven cleaner would. I don't thinkthis would cause any structural or surface damage, only cosmetic. Also,William Wynne pointed out in his conversion manual that sand blasting andbead blasting does what you mentioned in your previous post, and the changeto the surface screws up things like the lifter bores. He noted thatcleaners and pressure washing was the way to go and the truth about that isthat it cleans with no abrasion. If you only need to get the dirt off, thisis preferable.Although, some of us also want a little corosion removal and to provide alittle polishing action, this is not possible with pressure washing alone.At that point, it appears to me that you have two options, one is tomechanically polish with a small metal brush or a buffing wheel in a rotarytool, and the second is a light abrasive blast. The metal brush is similarto sand blasting in that it deforms the surface, which is no big deal to thelifter bores (etc.) because you would never get the brush in there anyway.The only other problems I have with the metal brush is that, one, it imbedsthe aluminum oxide formed on the surface down into the surface a littlewhich may cause problems with welding (but if you don't plan of welding, nobig deal) and, two, it takes a lot of work.Again, this is only my opinion and the thought process I used to get me tothe decision on walnut shell blasting. I would like to note that DJ, who isdoing an excellent job on his project, cleaned with oven cleaner and apressure washer and then wire brushed and otherwise polished his engine. Healso then welded the intake runners on. So I may be a little overboard inmy thinking since it can be done satisfactorily to the contrary.Robert HainesDu Quoin, Illinois
Re: Pietenpol-List: Re: walnut shells and airfoil talk
Original Posted By: "Robert Haines"
Robert,You are concerned with the safety of using baking soda as an abrasive butyet you are willing to use OVEN CLEANER and a WIRE BRUSH to clean thealuminum.I learned in A & P school that one should never use a wire brush or spunwool (unless it is an aluminum wire brush or spun wool) on aluminum as itwill embed tiny particles of iron (or brass in the case of using a brassbrush) in the aluminum which will then be the seed for dissimilar metalscorrosion.On the other topic, I can drink baking soda but yet would find ituncomfortable to drink oven cleaner!Baking soda is so mild an abrasive that it will not take anodizing off ofaluminum. As the anodizing is an oxide coating, I doubt the baking sodawould remove the natural aluminim oxide that would form on the aluminumafter it is manufactured. Besides, we normally etch the aluminum withphosphoric acid and then pickle it with chromic acid to form a "uniformlayer of corrosion (read as protective oxide layer)" to protect thealuminum.Chris Bobka----- Original Message -----
Robert,You are concerned with the safety of using baking soda as an abrasive butyet you are willing to use OVEN CLEANER and a WIRE BRUSH to clean thealuminum.I learned in A & P school that one should never use a wire brush or spunwool (unless it is an aluminum wire brush or spun wool) on aluminum as itwill embed tiny particles of iron (or brass in the case of using a brassbrush) in the aluminum which will then be the seed for dissimilar metalscorrosion.On the other topic, I can drink baking soda but yet would find ituncomfortable to drink oven cleaner!Baking soda is so mild an abrasive that it will not take anodizing off ofaluminum. As the anodizing is an oxide coating, I doubt the baking sodawould remove the natural aluminim oxide that would form on the aluminumafter it is manufactured. Besides, we normally etch the aluminum withphosphoric acid and then pickle it with chromic acid to form a "uniformlayer of corrosion (read as protective oxide layer)" to protect thealuminum.Chris Bobka----- Original Message -----
Re: Pietenpol-List: walnut shells and airfoil talk
Original Posted By: "Cy Galley"
Cy,I don't know the difference. I just remember that from the literature andtalking to Mike Thern. The term "industrial grade" was used.chris----- Original Message -----
Cy,I don't know the difference. I just remember that from the literature andtalking to Mike Thern. The term "industrial grade" was used.chris----- Original Message -----
Re: Pietenpol-List: walnut shells and airfoil talk
Original Posted By: "Christian Bobka"
SWAG It might not be quite as pure as say food grade but is cheaper andeither will work as an abrasive.----- Original Message -----
SWAG It might not be quite as pure as say food grade but is cheaper andeither will work as an abrasive.----- Original Message -----
Pietenpol-List: Re: walnut shells and airfoil talk
Original Posted By:> "Christian Bobka"
To the contrary, baking soda sounds like a very nice mild abrasive (althoughI have no experience with it's cutting action), my concern was that it wouldchemical react with the aluminum like an oven cleaner would and that's why Iwould be against using those materials. Also, I have reservation using awire brush as well. I must have reread my post three times here to makesure I didn't phrase something incorrectly, I thought I was pretty clear.Robert
To the contrary, baking soda sounds like a very nice mild abrasive (althoughI have no experience with it's cutting action), my concern was that it wouldchemical react with the aluminum like an oven cleaner would and that's why Iwould be against using those materials. Also, I have reservation using awire brush as well. I must have reread my post three times here to makesure I didn't phrase something incorrectly, I thought I was pretty clear.Robert
> Re: Pietenpol-List: Re: walnut shells and airfoil talk
Original Posted By: Michael D Cuy