Archive for November, 2010

 I decided to use the conventional method of attaching the meat to spit by fabricating the typical meat spikes. A few things I was particular about was I wanted no thumb screws for securing the skewers to the spit and I didn’t want a sloppy, loose round hole for the skewers to slide onto the spit. I didn’t want thumb screws because they loosen off and they are very difficult to deal with when they are hot and greasy while you’re fumbling with them when wearing gloves. I didn’t want round holes for the skewers because I want everything to fit snug and secure. The client asked for 8 skewers so eight is what I’ll make!

The skewers themselves are made from 304 Stainless Steel 5/16″ round bar. I needed to start by cutting 16 of them the 7.5 inches long. They got mounted in the lathe so that a 15 degree angle could be cut for each spike. Once they were spun up they got mounted in the bender and given a 90 degree twist.

The hubs were going to get fabricated with a 1/2 inch hex hole in them so they will slide securely onto the spit. I used cheap 3/8″ drive 1/2″ chrome sockets as the centers for the hubs. The main portion of the hubs was cut from 1.250″ x .250″ seamless steel tubing. In an effort to keep the costs down stainless steel was not used. The seamless tubing was cut to a length of .900 inches on the chop saw. They were then cross drilled using a .3125″ bit in order to have holes to accept the 5/16″ stainless spikes. Once drilled, the rough cut hubs made their way onto the lathe to get faced and grooved for welding. Each hub got a 1/2″ socket TIG welded into the center of them. One more trip to the drill press and the holes for the M6 socket head set screws got drilled. Back onto the lathe and the outer portion of the hubs got cleaned up. The set screw hole got tapped and then the scrap portion of the chrome socket got parted off. Then one last facing to clean up all the welds.

 

By this time all the spikes and hubs were fabricated and the joining of the two was all that was left. I built a very simple jig out of a 2 x 4 which would not only hold the pieces while they were welded but it would also make all the skewers consistent. After the welding the skewers all got a clean up, the set screws were threaded in, and they were complete.

 

I had separated the skewers into 2 groups. Half of them got the spikes mounted 90 degrees off from the hub when compared to the other group. This way the skewers could be double stacked to allow 4 spikes to be used on one end. It left the options open.

Next item on the list is to build the counterweights and the “back-up” emergency crank handle.

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A local automotive dealership was looking for a wheel balancer adapter to use on their Hunter Road Force wheel balancer. They needed an adapter with pegs deep enough to fit the rims on a BMW X5 E70. The available Hunter adapter is an adjustable, universal fit, type adapter that typically falls apart when you try to adjust it.

I started with a wheel hub from a E46 that has a wheel bolt spacing of 5 x 120. I machined out the center hub splines, plus a bit extra, in order for the hub to fit the balancer spindle. I machined off all rough castings in order to balance the hub out. BMW hubs typically use wheel bolts therefore I TIG welded in some studs. I then machined all the fingers from 1″ diameter solid alloy rod then drilled and Helicoiled the holes. I wanted to make the fingers removable in case there was a need for a different set in the future. This way I wouldn’t have to re-machine a new hub.

The new adapter has turned into the full-time adapter since it fits just about every BMW wheel the shop balances.

It was time to get caught up on all the little details that have been left behind. There have been multiple components that were only tack welded which have now been fully secured. I completed most of the “not so fun” tasks so as to not fall behind on the progress.

I had been waiting on an order of metal which were going to be my spits. The 304 Stainless Steel 1/2″ hex rod arrived on my door step on Friday so I was then able to use the weekend to get the rotisserie drives fabricated. I was able to place my bearing mounts in the proper locations and then weld them in. I built removable mounts to hold the dual rotisserie motors. I installed studs into the main frame to allow for the motor mounts to slide on and then get secured with custom made thumbscrews.

I wanted to have a place to store the spits and the grates when not in use. I choose to mount a couple of brackets to the front face of the main BBQ frame in order to be able to slide the spits in for storage. The grates each got a couple of hooks welded in below the ash drawers in order to allow for hanging.

Next item on the agenda will be to fabricate the prong adapters for the spit as well as a brace to clamp the spine of the lamb.

I shifted my attention to the rotisserie drive setup. The dual 7 foot spits are going to be made from 304 stainless steel 1/2 inch hex rod. I ordered the rod but have not received it yet however that didn’t prevent me from getting started on the bearing supports.

I’m not going to rely on the rotisserie motor to support one half of the spit. I will build 4 bearing supports to hold up each end of both spits. I designed the support using AutoCAD.

I am limited with my equipment therefore I am unable to machine the 1/2″ hex required to slide over the spit. I decided to use some 1/2″ drive 1/2″ impact sockets that I picked up for $2.30 as the main center support for the spit pulley. I started by machining the 1/2″ drive side of the socket out to .5625″ which would allow me to slide the 1/2″ hex rod all the way through the socket. I then machined the taper side of the socket down into a cylinder so that I could cross drill it and tap it in order for it to accept a 1/4″ fine thread set screw. The set screw will allow the socket to secure to the spit rod.

The pulley that is welded onto the socket, which in turn will ride on the bearing support, is machined from 2″ diameter mild steel. The steel stock is cut to .900″ wide then welded onto the socket. Once welded the rest of the machining is performed ensuring that the whole assembly turns out round.

There are 2 bearings for each end support. I machined bushings that support the bearings out of 1″ 6061 aluminum round stock. The bearings are then secured to the support using M10 socket head bolts.

The bearings mount to a bearing support cut from 2″ x .250: flat bar. The template designed with AutoCAD was used to plasma cut the supports. Holes were then drilled and tapped.

With the bulk of the main frame fabrication and welding completed I decided to focus on the trim work and stainless steel.

The main purpose of the BBQ is to use the rotisserie the bulk of the time however some grilling grates will come in handy and will keep the grilling options open. I welded up 2 grates made all from 304 stainless steel 5/16″ solid rod. They are both 12″ wide and rest on a couple supports that run the full length of the grilling area, this way the grates can be placed anywhere along the top of the BBQ.

The ash drawer handles were made from 3/4″ brushed stainless which I welded nuts into the ends for mounting of the handles onto the brackets. The main handle was done from 2″ brushed stainless. The ends were capped and nuts welded in as well.

Eventually the whole BBQ will be painted with high heat satin black BBQ paint. The addition of a few stainless steel highlights will give the unit some visually pleasing contrast.

Next task will be to focus on the rotisserie. Building of the spits and the mountings will hopefully give me some lathe time.

A number of years back I was watching Reverend Gadget on Discovery channel where he featured a metal bender that he fabricated. Any tool that I can add to the garage will be another tool I can pick from when fabricating. After looking over Gadget’s design, along with some other home-built benders, I came up with this one.

The base and bearing platform were made from 8 inch channel. The rollers were built from 2 inch x .500 inch pipe. I machined the rollers to fit a 1 inch alloy rod as the axle. The rollers were then TIG welded together to make them 1 piece.

I wanted to make the bender fully adjustable in order to facilitate different sizes of metal as well as different radius of bends. The adjustment slots allow for bearing movement. I then made room for a 20 ton hydraulic bottle jack. The jack is way overkill however it’s what I had available.

So far the bender works great. The metal compresses and expands great, no kinking. It actually crushes and forms the rounded corners, you find on square tubing, and makes them perfectly square. I’m unsure how tight a radius I can bend, I haven’t maxed it out yet. I also don’t know how big a tubing it will handle, I’m hoping I will be able to roll at least 2″ light wall square through it.

The only glitch in the whole set up is getting the rollers aligned parallel with one another after adjustment. If they are not aligned the metal tends to walk to one side of the rollers. I plan to adapt some guides in order to help keep the steel centered.