Match Plate Vibrator

I find myself having 90 extra minutes of free time 5 days a week due to working from home, so foundry season is off to a good start for me this year!

Thought I'd keep busy making some patterns, and I always thought ray-vin's "Air Vibrator For Match Plate Molding" project would be fun. I bet it would work for lost foam buckets too. An "All Flask Vibrator"!

Theirs is a little different than mine, they used lost foam and there is a spot where the ball bearing goes that would be an undercut situation for sand molding since I have no way of machining the undercut into the casting later. So I split that part in two, the draft on the two parts will form that groove once the two castings are bolted together with the parting line sides facing apart from each other.

I thought to myself, a vibrator just NEEDS to have kind of a funny name. Then I thought of alloyavenue.com member metalshop AKA the youtuber formerly known as DavidD AKA Backyard Foundry, and his famous homemade siphon nozzle waste oil burner.
You all know what it's called, some of you are probably using a Kwiky All Fuel Burner in your furnaces right now.



I'll worry about how to drill and tap the hole the air gun screws into right on the seam between the two bolted together pieces later... and whatever happens, I'll call it the price I paid for not wanting to make a corebox or get tooled up for machining right now. If I can't pull it off, at least I will have learned something the fun way trying!

First pour was a fail, one part failed to cast at all, and one had a shrinkage defect right near the gate.



Sloppily cut gating is what I'm blaming it on.

Tried again using patterns for the gating...



The base piece. Dymo embossing label tape experiment surpassed expectations!



A little bit of shrink and nasty stuff on the back side of this part, opposite the boss and the thick part the gate came into. I'll do better on the next one but it's certainly usable.



Top half of the base piece.



No shrink this time; first go at it, the hand cut gate was too deep, almost the entire 1/4" of the pattern itself. This time the gate was 1/8" deep. The drill starter holes came out nice too. There's 1/16" or so clearance between this side of this piece and the bottom of the cap piece, so the couple small lumps (mainly from the little extraction hole on the pattern) are not an issue. I spent 3 seconds and filed them off though, of course.



And the cap piece. I got the letters from a stupid little sign kit at the dollar store, just had to nip off some pins on the back side and they are ready to glue onto patterns! Considering I did not add any fillets to them (yet), I am really happy how those worked out!





Before I pour another (I have a bunch of sand buckets and I do want to make more match plates...), I'll try to fillet those letters so I can come back with pix showing if it made a difference. I'll try and get some comparison shots of the castings that had hand cut gating vs pattern gating too, it made a big difference!

Jeff

 

It'll go together like this. I have already thought of a couple way to have maybe made this easier, but I want to see it through so I can try it out before I start redoing patterns. If it works, great, if not, I don't mind having to rebuild or modify the patterns - it's fun!

Anyone think a 5/16" ball bearing is too small? If so I can either try to open up the inside part a bit on the patterns... or maybe just use 2 bb's?







Also, there is video.



Jeff

 

Extra casting time is great, glad your family is staying safe too.

Lol, paint. I should have thought of that. I found a tiny little ball tool that actually just about fits into the tight corners of the K's, so I started doing it the much, much slower and more difficult way, using tiny tiny blobs of the same 2 part epoxy paste I used to do the rest of the fillets. Got the first K and the W done so far...



Paint hates me anyhow.

And the first K is a little crooked.

Jeff

 

Happy to start seeing some casting work happening on the forum again.
Guess everyone has been hibernating??
Looking good Tobho.

 

Thanks guys. I have an ancient one somewhere but I couldn't figure out where I packed it away. Include "embossing" to your "dymo label maker" search and you can still find them. But you will have to scroll down past a bunch of non-embossing label makers to get to them... You can still get the tape too.

No thoughts on ball bearing size? I may need to remove some wood from two of the patterns to make room for a bigger one than 5/16" if that doesn't turn out to have enough mass to it. Anyone who's used one of the ones they have in real foundries know what size ball I should have planned ahead to make room for, with most of my flasks being 12 X 12?

I'll finish building this one either way, just wondering what to expect. I figured out how I'm going to clamp the two parts together to drill the 3 holes so everything lines up right. I had to make a special fixture out of really specialized materials with a hole drilled very precisely in the EXACT center. But now that's starting to get beyond the scope of the patternmaking section... I'm hopefully going to make a few of these, so I do hope to work any remaining bugs out of these patterns before I cast more of the parts.



The sad part is, I really did measure and try to drill that chunk of rusty steel on center. The pic doesn't quite do justice to how OFF center the hole ended up being.

Jeff

 

Aw nuts, I had a feeling it was too small. I used the ray-vin measurements more or less but sounds like I didn't sand off enough the inside part of the pattern to match where they machined their casting, to make room for a big enough bb. Well, we'll see I guess. Thanks ESC.

Jeff

 

The boss in the middle is a little taller than the rest, so there's a gap between the top piece with the KWIKY VIBE lettering on it and the rest, that is where the air comes out.

I assume these sort of devices use a ball because a ball rolls around easier than, say, a cube.

Straight(ish) walls would have been so much easier! This thing would be way more convenient to assemble if it were 2 castings rather than 3, it would avoid the need to drill and tap 3 tiny holes.

I've since got a copy of Stephen J. Chastain's book with the plans for his matchplate vibrator which seems to come fairly well recommended. It assumes you have a lathe which I don't, but the castings appear easier to assemble into a working device.

You can also buy these things, but where's the fun in that?

You can see one of mine assembled and installed here:
Carousel horse stirrup parts?

Jeff

 

I see what you mean now about a cylinder. Maybe that could work.

But when a ball bearing falls over on its side, it keeps on rolling...

Jeff

 

I meant a ball. Give it a try with a cylinder if you like, I think that might be easier to get jammed up than a ball but there's many ways to skin a cat. My patterns could still use a bit of tweaking, the ball does sometimes get stuck, but a bit of percussive maintenance frees it up fairly easily.

Jeff

 

If you can do machining, might be an idea to check out Stephen Chastain's vibrator design from the book Metal Casting: A Sand Casting Manual For The Small Foundry Vol. 1. The plans call for machined patterns and the one I made is way too fiddly to assemble more than a few times. Needs a bunch of extra drilling and tapping and having to drill and tap NPT threads right on the seam between 2 castings to work around the no lathe thing, so it is not really ideal... But it does work, at least for my small 7x7 flask.

This guy uses patterns built to Chastain's design and he says they work great:


That's if you even need a matchplate vibrator... I built mine only for fun, I don't actually cast anything in great enough numbers (yet?) to justify the use of matchplates other than for practice and for fun, ie. just to see if I can pull it off.

Jeff