Intro: The Windscreen Wiper Hog Roaster
If you've got a good crowd of people coming and you want a good party, why not hog roast on a spit?
I can give you several good reasons not to:
- You have to be up early
- You need to keep a dead pig somewhere probably overnight. Probably in a bath
- You need to hire a roaster which can be expensive.
I can help you with the 3rd option, because frankly they're extraordinarily expensive. So here's my how to build a cheap hog roaster for your party!
Box steel - I used 2.5mm thick 25mm square section steel. Cost about £50
A big stainless steel metal spike £35
Various metal implements for holding pig in place £35
4 Large ball bearings from China - £3
Random bike parts - we got ours from abandoned recycled bikes for about £5
A windscreen wiper motor - go to a scrap yard and ask for the cheapest most common model they do - ours cost £15.
A steel drum (£7)
Various bolts etc
You'll need various tools such as sanders - I used a welder but you could change the design to bolt the whole thing. We were learning to weld - and it really does show!
Why a windscreen wiper motor? These motors are incredibly powerful torque wise - with bike gears you reduce the speed and increase the torque. Our roaster managed 2rpm - that's pretty slow. Most commercial roasters go about 4-5rpm which is a little too fast.
Our design is wholly inefficient - it was organic. We welded bits on here and there. We couldn't adjust the height of the spit because of our gearing method. But it works and cooked pork is the end result. if we needed to raise or lower the fire, we did so with welding gloves - there was lots of people there - it was a party after all - not a lone project. Also we oversized the project for bigger heavier pigs for the future - who's only going to use a roaster once! We ended up sticking chickens on the end of the roaster which came up lovvverly.
(The silver foil on the ears is to stop them burning off over the course of the roast!)
Step 1: Concept Design
The first stage in my project was an email to the usual crew of makers saying "I want to build a pig roaster for my party"
To which the reception of enthusiasm was not high.
One of my friends was bored and created a design (in MS Paint) based on my first incoherent email from down the pub. I told him I had problems visualising and needed a pig and more fire.
This should give an indication for the general thoughts and design methods that went into this, and why we had so many problems following the blueprint.
Step 2: Drilling
We thought of several different ways to keep the spit turning with as little friction as possible - my favorite was using 'pig balls' - these being large 25mm ball bearings (5 for £3 from china)
We cut two holes in the T bit of metal with a 22mm drill bit. Using files, we made sure the edges were nice and smooth and eventually put some right angle brackets just in case the balls popped out and went left or right - this 'safety' feature was to stop the roast suddenly falling to the ground. It was the simplest way to deal with the issue and the cheapest. It does mean you have to adjust the fire rather than adjust the height of the roast.
Step 3: Bike Bits
We went to the recycle centre. Our roaster is to be used at events for fundraising for scouts, so we got a bunch of used components quite cheaply. Look for similar recycling schemes where possible. You'll need
- a crank (preferably with pedals - this gives you a manual option if you need it.
- a rear cassette
- single rear cassette
- chain tensioner
I used a bit of scrap steel on the single rear cassette to fix it in place, drilled a hole in the centre for attaching to the windscreen wiper motor.
The crank had 25mm ID (Internal Diameter) stainless steel shaft collar welded to it. I didn't have any stainless welding rods and I welded this direct with a steel welding rod. It held, it's not pretty but did the job. I'd recommend using proper Stainless Steel 304 rods.
The main cassette was just bolted on in the relevant place. The chain tensioner was fixed on with bolts, as was the motor - mounted directly to the frame on the bit of metal it was attached to on the car - lots of reuse going on. We used a spring attached to the motor which was also attached to the frame to tension the bottom bit of the apparatus.
The whole thing was powered by a bench power supply. It worked best on the 5v setting at 3amps. We got about 2rpm which is fantastic for roasting at. The amount of torque the motor produced was astounding - when running I couldn't stop the pole spinning with my bare hands.
Step 4: Welding the Frame
There was nothing particularly complex about the frame. There was absolutely no planning in this at all.
As per the previous stage, we'd welded the bearing block to the top in a T fashion.
We then extended this by making it into an I (that's a capital i, silly fonts). I then added stability by putting on a leg coming 90' out of the base.
Later, when we'd added all the gears and motors etc, we added the cross bracing. This is because the chains and motors would need to work around the cross braces without interfering. See video below - the cross brace eventually went above the main sprocket below the crank.
Finally we added two 90's bits on the bottom of the I (that's another capital i) with two holes in it and laid two 2m box steel lengths which bolted to them. This meant it would stay relatively stable and be easily transported.
Step 5: Adding Accessories
There's no delicate way of putting this. You're going to ram a large stainless steel rod up a pigs bits. You'll also need things that will stop it spinning. I used various spikey things. Just search for hog roast on ebay and you'll find all sorts of things.
I also used several stainless U shaped bolts with a flat stainless washer that went across both pins to adhere the spine to the metal pole. They're cheap if you don't buy from a hog roasting company.
One of the spikey things I ordered was just too small ID wise - So I angle ground a cut in it and welded some steel in between after hitting it hard with a hammer. This made it fit. Again, you should use 304 rods, or alternatively read the ebay auction description carefully.
Step 6: Fire
Finally we needed a bed for the fire.
I got some old perfume barrels and cut them up with an angle grinder. Make sure yours is good enough for the job - mine was a bit wussy and used about 4 disks. Wear goggles or you'll never see again. Also fire proof trousers. Mine now have holes in them.
Having never dealt with a dead pig, we didn't know how thick it'd be. We were definitely winging it. In the end, I used two old school tables to provide the height needed to get the sections of barrel high enough to warm the pig. There was also bits of wood underneath for final adjustment.
Also I was worried about the weight of the pig stalling the motor. We tried strapping a rucksack filled with weights as a dry run, but it slipped around terribly and stalled the motor. So I made an adjustable weight using a steel bar offcut and another shaft collar. We didn't end up using it.
I hand sharpened the point on the stainless steel rod with a file. It took about 25-30 minutes and I was very pleased with the outcome. It almost looks professional!
Step 7: The Pig
One of the reasons I married my wife is she puts up with me. See second pic.
The pig was due to arrive friday late afternoon and was for the next day as I'd need it at 5am.
It arrived before lunch on a very hot day.
Into the bath it went, with plenty of cold water. I wasn't prepared for such an early arrival so I rushed out and bought about £20 of ice. And wrapped it in towels. Next morning some ice still remained, so it worked for me.
The point is, have a plan to store the pig. The 2nd point is, be prepared for failure and stupidity.
Where does one get a dead pig? From the farm direct of course, it's much cheaper that way. Most places need 7 days notice.
You want about 1/2kg of uncooked pig per person. I worked out I'd need about 35kg for about 70 guests - that came to about £135. In the end the slaughtered pig weighted about 28lbs - I'm glad I got a lighter pig - I've still got some in the freezer a year later, even though about 80 people turned up.
Step 8: Preparing!
First things first, light your fires. My first fire wasn't for the pig. It was to remove the wasps nest (yellow jackets in the US?) anyway, they'd setup shop next to the roast and it was a joint party, my 1yr old son and I. Fearing stinging beasts I disposed of them with various forms of fire.
Getting the pig onto the spit was much easier than expected - it slid on. We couldn't get the pole out of the mouth though - eventually the spike tore its way out of the mouth.
I used stainless steel wire to secure the feet.
Wash all implements!
I sowed up the pig using a bit of stainless steel rod I'd sharpened one end, hammered flat and drilled the other end as a giant needle. The belly needs to be closed otherwise it flaps about.
Score the pork for extra tasty crackling (with a big sharp knife)
Step 9: When It All Goes Horribly Wrong
One thing I really didn't expect was that the belly flopped around too much. Also we probably shouldn't have started drinking at 9am.
I'd added some U pieces to hold the spine to the bar, but the belly flopped round and stalled the motor.
Disaster! I'd ordered stainless steel wire from ebay, but not enough - I thought 25m would have done the trick but apparently not.
So off I went looking for anything that wasn't galvanised (galvanised will poison your meat) and got a big fat 0.
In desperation, I found a replacement BBQ rack in homebase for £5. I bent this round the belly and used the leftover wire to bond it together. Success!
This had taken some hours and unfortunately we'd had a miscommunication in the heating department. I'd left my friend Gary with a laser thermometer and instructions to maintain it at 170 degrees. Unfortunately it'd got reset to Fahrenheit so the pig had been 'roasting' for about 4 out of the 7 hours at about 77'C. Very slow roasting. The pork was barely warm.
We jacked the heat up to about 300'C and the pork tightened up - as the party started in less than an hour at that point we really needed to get it going quick. We did get it properly cooked in the end, but slow roasted it was not!
Step 10: Drink, Party and Be Merry!
Obviously you've been up since 5am
You've been running around madly trying to find bits of metal to finish the project which is now very much in its final stages.
So hopefully you've prepared 15 gallons of home brew ready for drinkin'
Once the pig is cooked, take it off and let it rest - we gave it half an hour under tinfoil and more blankets to for the juices to release (this porker needed all the help it could get)
If you're very lucky your friends will help you out carving as well.
The pig head is a source of much fascination - we put it on the platter with the rest of the meat and all sorts of people played with it. I pulled the tongue out with a pair of pliers - it was extremely tasty. Like gammon!
Serve with fresh buns, apple sauce and stuffing.
The head finally ended up with a friends Alsation.
Step 11: Aftermath
The aftermath is lots of left over pork!
Think about how you're storing it etc. I vacuum packed a lot for later consumption!