Forging a pestle and mortar...how?

[Aaron J. Cergol]

Howdy all,

I was asked today if I would be able to forge a mortar and pestle, I said yes, thinking about several ways to go about doing it. Thinking more on it now, I'm curious to know which might be best for such a thing. Here's a couple of the ways I was thinking about...

-a 3/8"-1/2" plate, cut into a circle, worked hot into a form. The downside to this would be the hammer marks inside, and also not having a steady base. any suggestions for a base? Also, getting an appropriate depth could be troublesome.

-a circle or square of VERY thick plate, say 2"+. Work it hot by bashing a large diameter mill ball into it. this would have the advantage of having a sturdy footing, and have relatively few hammer marks. the downside is actually bashing said mill ball into it. I cannot imagine it being fun or safe. So, that being said, I do have a 20ton fly press that I could use to press the ball into the steel. It's in my storage unit, but I think I could get around that. The other downside is again, the depth.

depending on how large he wants it, either one would be quite doable, but the larger he wants it, the more difficult it will become.

How would you go about making it, or do you think either of these ways would work?

Thanks,

Aaron

[Fosterob]

I think since your flypress is in storage you should ship it to me so I can use it. Let me know how much the shipping costs Might be kind of light depending on the size of the depression you want but I would try flypress. Large hydraulic would be best.
Rob

[BIGGUNDOCTOR]

I would take a different approach. I would consider using a hunk of round bar, and driving in from the end with increasingly larger sized punches till I could get it onto a horn, or similar device. The bottom could then be necked down to form the base.

Most mortar, and pestles are made incorrectly. If it is properly done you can lightly cup the end of the pestle in your palm ,and roll it around the rim of the mortar. As the pestle rolls around the rim it also rotates on its axis forming somewhat of a planetary action. The one I have is made of cast iron, and it gets used regularly in the kitchen grinding spices. Having a smooth interior may be somewhat of a detriment. The pestle I have is as cast on the bottom, and not smooth at all. This roughness helps grab the items being ground instead of just pushing them out of the way. The pestle looks like a small baseball bat giving you a wider area to palm the end. Most of the M&P's on the market are designed to pound with,as they are too shallow and wide, which makes a mess most of the time.

Another option that would be more lapidary than smithing is to make a molcajete.

[macbruce]

I have done pretty much what you have described by hammering a 3 1/2'' dia. mill ball mounted to an upper PH die into a 6'' x 1 1/2'' round plate......I didn't have the correct dish size I needed for leaf forming so I made one...........As far as pushing a 4''+- ball into 2'' plate say 2'' deep the 20 tonner can stay in storage, I'd say more like 50ton..........Good luck with it............mb

[ThomasPowers]

As has been mentioned most seem to have been cast.

However the traditional method to forge one would probably be to indent a fairly heavy bottom slug to get the rounded interior bottom and then forge weld the walls to it.

[Aaron J. Cergol]

I do not how well I feel about my forge welding skills to pull off such a venture Thomas.

I like the die idea, but I lack a large enough press for it...unless Thomas thinks it's up to snuff-I'm fairly certain you and I own the same model Hopkins...

Thanks for the ideas folks, but I'm still needing a doable one. Perhaps dishing some 3/8" plate into a deep form, and then welding or riveting on a ring on the bottom for a base? Heck, nothings saying that it even has to be welded or attached. It could just sit on the ring and with one hand holding it steady, it wont go anywhere.

what do you all think?

Aaron

[ThomasPowers]

Well for modern methods a fast easy method to rough it in would be to use high explosives. The do it all the time at EMRTC out here.

[bigfootnampa]

All the approaches discussed so far seem exorbitantly expensive to me... in terms of forge time and equipment. Personally I would get a piece of high grade tubing in the desired maximum diameter and forge it to a neck between the open end and the base... then I'd forge weld it closed at what now will be the bottom of the mortar. Next I would flare the base a bit to give a wider stance finishing with a sort of goblet shaped mortar. I'd say that 1/4" wall tubing would be worlds aplenty as the tubing will thicken a lot where you neck it down. This could give you a near optimal shaped mortar with an elegant shape and sturdy base for a reasonable investment. The mortar neck would make a nice place to hold on as you grind in it. You might want seamless tube for it but considering the price differences I'd probably try it with regular tube first. Even black pipe might work but if you are making a good sized mortar you might find that the forging stresses will open the welded seam.

[Aaron J. Cergol]

I know how to neck down smaller pipe up to about an inch in diameter, but how would I go about doing this on a large scale of say 4"+ in diameter? I suppose the same way I would neck don normally-with either a spring fuller or a top and bottom tool, but I just imagine it being more prone to collapsing upon itself... also, I can see necking it down to a reasonable thickness and then flaring the base, but how would I fill the hole then? You say forge weld it, but I see that being a bit problematic in terms of actually hating that area.

I am liking this idea, but I'd like to figure out a bit more about it.

Thanks

-A

[bigfootnampa]

I have not actually done this on the 4 inch tube scale but I have done it with smaller pieces. The center hole becomes quite stubborn as it gets nearly closed but steady patient forging and some borax flux has been successful for me. I would use my Anyang to do the necking down (it loves that kind of work). If a larger tube gets too stubborn about closing up I expect that I would add a short chunk of solid rod and weld that in to close up the center hole. Collapse is pretty unlikely I think... as the tube gets necked down it will thicken dramatically.

[Sask Mark]

Just a thought, do you know what the mortar and pestle are being used for?

I used to use them in analytical labs, and they were made out of porcelain, so they were non-reactive and smooth to prevent cross-contamination between samples. We couldn't use one that was forged out of a mild steel for our purposes.

[Unforgivun]

Just a thought, do you know what the mortar and pestle are being used for?

When it comes to a mortar and pestle this is the most important question to ask. My primary income comes from working in a compounding pharmacy where I have to mix drugs/chemicals to produce creams, capsules, suppositories, you name it, chances are I've made it.

That being said, mortar and pestles are often completely unusable. For instance, we have wooden ones that customers have given us. Pewter ones etc. When it comes to drugs, just like food, you have to be wary of reactive surfaces. This is why aluminum pans are now almost always lined with steel, or a non-stick surface. Aluminum is highly reactive to acids, so lemon juice, vinegar, even alcohols all get a metallic taste from aluminum.

BIGGUNDOCTOR stated that he was using a cast iron mortar and pestle in his kitchen for grinding spices... that means that every time he grinds those spices, he's adding little bits of cast iron into his diet. Not saying theres anything wrong with that, every time we use a metal spatula on a cast iron skillet we're doing the same thing. He also stated that the pores in the cast iron help to hold onto things. Let me tell you, I absolutely HATE breaking in a new mortar and pestle. The porcelain ones (Wedge-Wood) are much easier to work with when they are new than glass. It takes the glass ones a good 40 uses or so to start getting those scratches that makes them really nice. The only thing he stated that I directly disagree or take fault with is that he said most modern mortar and pestles aren't made correctly, that they're made for pounding. That's sort of the purpose.

Just remember, we're used to seing it in logo's of pharmacy's. That's not to say that the shape we're used to is absolutely correct. A "mortar" comes from the latin Mortarium (spelling) and basically means receptacle for pounding, and "pestle" comes from pistillum (again, spelling) and basically means pounder. So basically, a mortar is any receptacle for pounding an object. Thus a spoon swage is a mortar. And a pestle is any bat shaped object used for pounding. Throw out the rules, step back, have fun with it. Chances are whom ever comissioned the item doesn't plan to use it, but to have it setting on a counter for looks and if thats the case, just make it look CRAZY. The International Journal of Compounding
uses mostly purely decorative mortar and pestles on the cover of their magazine every month. Might be able to find some ideas looking through some of those.

[MattBower]

The International Journal of Compounding
uses mostly purely decorative mortar and pestles on the cover of their magazine every month. Might be able to find some ideas looking through some of those.

Great suggestion. Back issues (with cover photos) here: http://www.ijpc.com/Backissues/

I had no idea mortars and pestles could be so interesting.

[Aaron J. Cergol]

I agree, fascinating stuff' lots to learn.

Well I ended up making a bowl from 1/2" plate dished on the anvil, and then welded a flared ring to the base. His father loved it. I had tried the pipe method, but didn't work out. it got so thick in the center that it became difficult to move-difficult to heat that middle section too. I would like to eventually try it again though.

Aaron

[SmoothBore]

Well, ... it might offend some sensibilities .....

But if I wanted to make a "forged" mortar, ... I'd start with an appropriate diameter slug, of Stainless Steel round bar. ... and rough the cavity out, on a lathe.

Then I'd forge the final shape.


But that's just me .....



.

[beth]

smooth bore - i dont think thats a bad idea, you need to get some real nice weight into the mortar, yes you do hold onto it anyway, but even so, i reckon the lightweight ones and rubbish. it can be shallow, but then it needs to be lovely wide dish, and very solid and heavy.. and i would agree as an avid user of this tool in my kitchen, it does need some key in the bottom, even if its subtle. i will be really interested to see how you make this just sorry i cant think of a better method... have you seen the wonderful bowls rory may makes on his press? some of those look heavy enough to make an effective mortar..