Author Topic: Group buy-group pour, bronze 24 PDR Coehorn golf ball mortar (Read 28256 times)

Cat Whisperer · « **Reply #150 on:** October 13, 2011, 02:44:59 PM »

(WAY off topic - where do/did we get....) I a kid in H.S. who ... (not posted by better judgement)

OK, so lost-wax test castings - then to a more durable pattern? Maybe by summer?

Meche_03 · « **Reply #151 on:** October 13, 2011, 06:26:59 PM »

Any thoughts on making a wooden mold on the lathe and having the design cast in green sand? Won't have the same quality of finish but it may work out better if the foundry has more experience with sand casting. I wonder if someone could make the "wooden" mold on a rapid prototype machine from a cad file. I'm not trying to direct the project just trying to think of other possible ways it could work out. It appears there is a significant number of us powder monkeys interested in the end goods

RocklockI · « **Reply #152 on:** October 18, 2011, 03:26:05 PM »

Here Wego

This is the last best effort I am giving this project .
I have discarded completly the notion of molds or poured wax.

I am now going to make these things one at a time on Seacoasts lathe ,and with their input.

Mike and I made some new aluminum jaws for the lathe ,we turned them today ,boring out the radius on them . They are made for wax only .

There should be plenty of grip on the wax to ...hopefully.... use a shaping tool that I've been working on . I ordered some sleeve sanding cylinders which will go onto MT's radial, reciprcating sander . It spins a cylinder shaped sand paper in the center of a flat plate ,at the the same time the clyinder goes up and down (radius freindly)

Here are the jaws perfectly made to grip a length of the wax.

This is a pic of the shaping tool roughed out . I traced a 1-1 scale drawing I made on the white paper . Then cut out one side of it ,trimmed to perfection and then taped it to the steel to be made into the shaper . Then the steel was cut close to the final shape .

I am now waiting for the sanding thingamaroos to show up then I'll finish the cutter

This is the same as the above except with the positive peice of paper removed .

The piece of steel has a large apendige for holding onto for making then it will be cut off .

So if all goes well they will be delivered to my caster here in Co. and then distributing to the folks .

I still dont know for sure what DDs will cost to be cast . Mike has bought some very thick walnut to use as beds . We may offer them complete with bases .

Gary

Spuddy · « **Reply #153 on:** October 18, 2011, 04:04:59 PM »

If people have been thinking about speaking for one of these mortars then the last statement made by Gary about the thick piece of walnut should convince you to speak up for one now.

Double D · « **Reply #154 on:** October 18, 2011, 07:12:35 PM »

Walnut? Walnut is to pretty to be painted!

keith44 · « **Reply #155 on:** October 18, 2011, 10:15:20 PM »

Quote from: Double D on October 18, 2011, 07:12:35 PM

Walnut? Walnut is to pretty to be painted!

+1

Besides I am going to be cutting down a diseased Walnut tree in the very near future (likely this coming weekend) and will salvage a section for future use

Victor3 · « **Reply #156 on:** October 19, 2011, 12:57:39 AM »

Gary,

I suspect that even with wax you'll get some chatter cutting such a large radius.

However, years ago someone showed me a trick to clean it up. On the final few .001's, turn the lathe off, take the spindle out of gear and shave the last bit off rotating the chuck by hand.

RocklockI · « **Reply #157 on:** October 19, 2011, 07:52:52 AM »

Who said anything about painting !

Here is the latest kick in the head

......I got a phone call this morning are you sitting down DD?
Your wax is gone the investment cracked and it is a total loss

Believe me Doug I feel your pain ..... The foundery will do the next one free of charge .

Yes chatter is a concern we'll just have to see , one thing Mike and I talked about is cutting the shaper in half so there would be less surface area . Thanks for the hand turning tip Victor 3 I'll try it if needed .

This was very disapointing news ,but Tony has taken a personal interest in this cannon stuff as wants one too! If anyone would like to see the foundery online here is a link ,
http://www.artcastings.com/

Sorry Douglas , but it isnt a science , it is an art .

Gary

Double D · « **Reply #158 on:** October 19, 2011, 07:58:44 AM »

Gary, Nothing ventured, nothing gained!

I have some steel in the shop and maybe this winter using my newly learned introductory CAD skills I will draw up and make one these in steel for molding.

flagman1776 · « **Reply #159 on:** October 19, 2011, 08:32:12 AM »

Gary,
I am sorry. I know you put a lot of yourself into the work. And a lot of effort. It is a real kick in the teeth. I'm surprized you can still be civil. <<< sigh >>>
Russ

GGaskill · « **Reply #160 on:** October 19, 2011, 08:00:23 PM »

Blown moulds is one of the reasons to make rubber moulds instead of investing the original wax. It runs up the cost as the rubber is not cheap but you can make another wax without too much work and without the emotional loss of all your effort that is in the original.

RocklockI · « **Reply #161 on:** October 19, 2011, 08:54:09 PM »

George, the whole idea here was to make affordable Cohorns .Affordable means very little extra handwork or chasing . (vent drilling excluded)

This is the reason I insisted on a cast in bore (no maching),which is supposed to be taboo ,I'm reaching abit to find out what I can (get away with) acomplish and a cast in bore IS doable because Caleeco foundery did it

. Then they beat it all up .

Any mold I have ever seen has left parting lines ,believe me when I say parting lines suck

! I only say it because that has been my experiance in trying to clean them up !
They suck

Then theres the lag time from order to completion for the waxes . BAH !

This is why I am trying to produce perfect unmared examples straight off the lathe in a short order .

Of course the fact that engaging a professional mold maker would be upward of 1000 bucks more or less , but nobody knows (the trouble I seen

...)how much till it is done AND making good copies in wax is an issue too .
Molds have bugs too and may need adjusting = Mo $$$ and this IS the main reason for not "investing" in a mold and I anit talking casting investing.

Tomatoes ,Tomotoes , Potatos, Patatos , I decided to do it this way. I'm not ready 'to call the whole thing off '.

And besides George I did NOT have any GALL DARNED EMOTION TIED UP IN THAT WAX ! MUCH .

Gary

flagman1776 · « **Reply #162 on:** October 20, 2011, 09:30:07 AM »

Not that I know squat but... because the bore is "straight" bore to chamber with no taper, I'd think would make casting in place impossible. I have limited experience with lead casting and fiberglass boat molding but was given to understand that some "draft" (taper) was manditory in order to separate the item from the mold. I think it would be no negative to have some taper to the chamber... If trying to cast the bore in place...
maybe some other removal technique is required. Maybe the foundry should not be asked to do it.
maybe a tapered bore could be done with minimal turning to make it straight.

None of this touches on the mold problem... You've got to get a mold before you can pour into it.

RocklockI · « **Reply #163 on:** October 20, 2011, 01:36:52 PM »

The "mold" in this case would be the investment that the bronze is cast into .

This investment that holds the hot bronze in shape untill cooled then it chips off with no real problem ,some places use sand blasting ,some use glass beads .

I have asked them about quenching in water like the powdery investment I have used .
The investment shatters on contact with the water and this is even in a steel flak Kawoosh !

They they give me a deer in the headlights look .
The water boils like mad instantly in a few minutes you reach in and out comes whatever was cast .It still has an 'orange peel' on it and elbow grease with scotch brite takes that off .

I did get news today that the linstock and tail spike are almost ready

,they have been cast and just need spruing cut off and weighs taken .... I am real ready for some good news !

Gary

RocklockI · « **Reply #164 on:** October 22, 2011, 03:59:56 PM »

Today we had some luck finishing the shaping tool . The sanding cylinders came in yesterday,So I took them to Seacoasts shop . Here are some pics of what got done today .
As you can see this is the shaper roughed out .

Here is a photo of one of the most usefull tools I've ever used

The next two show the finished edge .

These next two show the orientation of the shaper to the wax .The wax is held in place by the newly made jaws on the lathe .

Now I just need to cut the shaper from its"handle"

and we are ready to go.

Gary

seacoastartillery · « **Reply #165 on:** October 22, 2011, 05:07:48 PM »

And from Gary Lorenz today, "Now I just need to cut the shaper from its"handle"

and we are ready to go."

What you mean, we, Kemo-Sabe?

Tracy

GGaskill · « **Reply #166 on:** October 22, 2011, 05:31:02 PM »

No, that line is, "What do you mean we, white man?", as all the Indians in the world are riding down upon them.

RocklockI · « **Reply #167 on:** October 22, 2011, 06:44:31 PM »

"I" is what is should have said ,all apologies

.
Gary

flagman1776 · « **Reply #168 on:** October 22, 2011, 06:50:50 PM »

GGaskill · « **Reply #169 on:** October 22, 2011, 08:00:25 PM »

Allegedly "Kemo-Sabe" is a 2 word combination in some native dialect...

It is a Hollywood construct and probably is not any real words of any known language. Many comedians have "translated" the name to fit their needs.

Victor3 · « **Reply #170 on:** October 24, 2011, 12:15:40 AM »

Gary,

I can't tell from the pics but did you put a relief angle below the cutting edge? Will cut better that way and help avoid chatter. Easy to add one by placing a small tapered (like 5 degree) block between the cutter and sander table.

Or, if you don't want to mess with that, setting up the cutter so the top surface is ~.06" below C/L of the wax will help some.

DaveSB · « **Reply #171 on:** October 24, 2011, 05:52:03 AM »

done yet?

? hahaha, couldn't resist Gary!!

RocklockI · « **Reply #172 on:** October 24, 2011, 03:20:24 PM »

No ,Vic3 no relief ,I will put it a few .000" down below center and the radius of the wax cylinder will provide the relief .

Dave I sent yours two weeks ago ,havn't you got it yet !

BTW you havn't paid your bill ,so I'll bill you . BUT No Soup For You !

Gary .

gunsonwheels · « **Reply #173 on:** October 24, 2011, 07:38:43 PM »

As I have followed this thread it appears there is some confusion about casting methods and the rules associated with each of the processes.

I have tried to remember the various rules associated with the various casting processes. Draft angle has been mentioned and I believe that is only important to die casting and sand casting. Die casting it's important to remove the finished part. Sand casting it's important to remove the pattern without wrecking the mold for the pour. With investment casting the pattern is made from wax and the mold sprayed around it along with the sprue. The wax is melted and pours out of the mold leaving the finished cavity ready to pour the molten metal into. After the pour, the mold is destroyed to remove the finished part... draft angles do not apply. I think what Gary is doing is giving up on making a master from which multiple wax patterns would be cast and is machining them individually with the shaped cutter.

I could be all wrong in my assummptions however... some corrections Gary...??

GOW

DaveSB · « **Reply #174 on:** October 25, 2011, 04:10:14 AM »

Quote from: RocklockI on October 24, 2011, 03:20:24 PM

Dave I sent yours two weeks ago ,havn't you got it yet !

BTW you havn't paid your bill ,so I'll bill you . BUT No Soup For You !

Gary .

HAHAHAHAHAHAHAHAHA!!

flagman1776 · « **Reply #175 on:** October 25, 2011, 04:34:15 AM »

RocklockI · « **Reply #176 on:** October 25, 2011, 12:59:19 PM »

Today was a great sucsess !

All pics below are courtesy of Tracy !
The shaper tool worked like a charm .

This mortar shows the effect of the tool .
First cuts .

Another view of it.

Here it is done ,and then the second is with my thumb hiding the 'tit' because it won't be there later .

Hopfully this will be an answer .
Gary

Cat Whisperer · « **Reply #177 on:** October 26, 2011, 01:36:53 AM »

Thanks for the pix!

SEEING the setup for the profile scraper is worth many times the price of admission! I have a big piece of 3/16 S7 that will now get cut up into lots of little pieces.

gunsonwheels · « **Reply #178 on:** October 26, 2011, 04:39:35 AM »

flagman1776:

Quote

Thanks GOW for getting what I was missing. I get it now. With lost wax, the investment is later destroyed in the part removal so there is no need for "draft" to allow the 'as cast' part to drop free. A little bit of knowledge... is dangerous. Thankyou for gently adding to my knowledge.
Russ

Speaking of little knowledge... I am not sure exactly what the term "investment" refers to whether it is the part itself or the sprayed on mold or the wax that is "lost" by melting it out of the mold... I always thought it was the part itself but I could well be wrong... Investment casting is also known as "Lost Wax Casting".

I do know making a reusable master to cast the wax for a reasonably complex part can be very difficult and sometimes impossible... after all... some reasons for going to investment casting is to achieve complexity in details, no draft angles, accurate dimensional and finish quality. Unrelated, but when we studied it in college we were told Ruger Firearms Company was near the top of the heap on knowing how to do it well as all their handgun frames were investment cast... GOW

DaveSB · « **Reply #179 on:** October 26, 2011, 05:42:16 AM »

Quote from: RocklockI on October 25, 2011, 12:59:19 PM

Hopfully this will be an answer .
Gary

If nothing else, it'll make it WAY easier to make more the next time the foundry screws it up

Poll

I would buy...

Author Topic: Group buy-group pour, bronze 24 PDR Coehorn golf ball mortar (Read 28256 times)