Archive for January, 2012

Well I did some testing of the Reil style propane burner that I built for my future foundry furnace. I must say that I was pleased with its initial performance. Last week I had pieced together a Reil style burner. Since then I have collected a 15 foot propane hose, a 20lbs tank of propane, the required fittings to allow the hook up, a 0 – 60 psi pressure gauge, as well as a 0 – 30 psi propane regulator.

I choose to plumb the pressure gauge right in at the nozzle instead of at the tank thereby ensuring I would know exactly what pressure the nozzle was getting. As I mentioned in an earlier posting I had cut the burner flare at too steep of an angle however I chose to use it as a learning experience and see what kind of difference it would make. So with the propane tank connected to the burner I headed outside to see what kind of damage could be done.

I thought that a video would be more interesting than any kind of descriptive writing I may come up with so below you will see the inaugural testing. When viewing the video you can watch the pressure gauge at the nozzle. I was able to adjust the propane pressure all the way from under 1 psi up to 30 psi. Take note that the “12 o’clock” position on the gauge in the video is 30 psi. The video demonstrates adjusting the jet position first by using water and then the burn section shows the effects of different pressures and different choke settings.

So after the video was shot I switched the burner flare over to a different, and proper 12:1 ratio, flare. I then lit the unit up to see what kind of performance difference was evident. With the proper flare I was unable to achieve propane pressures past 20 psi. There are, however, other variables at play. I am one size bigger on my jet then I ought to be so I am going to hold back any official reviews until I have time to machine a #60 jet.

So with moderate success I continued on with some engineering of the actual furnace. I was throwing different numbers around and determined that in order to achieve the amount of BTUs required for the furnace I am planning to build I would need 3 Reil style burners. Hmmmmmm…I could do that or I could just go bigger. I am undecided however I figured it was probably worth my time to prototype a bigger burner which will have a 2″ nozzle as opposed to a .75″ nozzle. Since then I have collected all the parts required for the bigger burner and will try and hunt down some time to construct it. If the bigger burner is a success then the continued testing of the smaller Reid type burner may come to a halt.

The burner I am building is Reil style burner which will have enough output to fire a small aluminum melting foundry. I will not go into the physics behind the burner since this has already been done by Mr. Ron Reil himself. If you are interested in learning more then check out Mr. Reil’s site here.

The Reil burner is a very low budget design that allows anyone to piece one together using standard gas pipe fittings. In my case since I have access to a lathe, welder, and mill so I chose to build it with a few slight modifications. None of the changes that I did affects the original function or performance.

I chose to make a couple of changes to the original Reil design. The first one being that my burner is designed to have the jet size changed easily and quickly. The original burner design is simply and 1/8” brass nipple with a jet hole drilled into the side of it. I decided to make my own mini jets out of replaceable brass 1/8” pipe plugs. This way when it comes time to tune the burner I can easily experiment with different jet sizes. The second change I made was to how the flared nozzle is fabricated. Those people without a lathe have a greater challenge when trying the build an accurate flared nozzle. In my case I plan to machine the flare to precise tolerances.

So I started out with some basic gas and brass fittings. The rest of the parts will be used from metal I have laying around the shop. The combustion chamber and the nozzle are simply a ¾” – 1 ½” pipe adapter threaded to an eight inch section of ¾” gas pipe. The 1 ½”  nipple used as the air intake duct was cross drilled to accept the 1/8” brass pipe fittings that will make up the gas jet assembly. I machined some collars, with set screws, and welded them to the sides of the intake pipe. The collars would allow me to align the gas nozzle on 2 planes and then lock it down into position.

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Of course there are flow dynamics that enter into the equation. For example some of the unknowns are the amount air flow the intake will allow as well as the exact jet size that should be used. I am unsure if I will be running too lean or too rich. I can easily alter the jet size to accommodate however changing the air intake size would require a complete re-do. Anyways…I am basing my 1 ½” intake pipe calculation on other people’s experience. As far as the jet size goes Ron Reil recommends starting with a #60 jet. Since my #60 drill bit was previously broken I stepped it up one size to a #59. In order to be able to idle the burner down I opted to add on a choke assembly to the back of the intake. It is nothing more then a leftover 2” aluminum disc (one that I had prototyped for the tank clock) and a 6mm SS threaded rod. This way I can accurately control the intake air flow.

Onto the flared nozzle. The flared nozzle is said to work best with a 12:1 flare ratio over a length of 1.5”. Well it was Sunday afternoon that I was building this and I was using metal that I had. Since I had no heavy wall 1” ID cold rolled I drilled out solid stock to suit me needs. Drilling out the 1” center took awhile but came out beautiful in the end. Right on, all I have to do is flare it. Well this is where the measure once and screw it up permanently rule comes into play. I set my compound rest angle wrong and cut my flare too steep. Oh well, no fixing it now. I will use the wrong cut flare nozzle as a learning experience when it comes time to tune the burner. I will plan on cutting and new, and correct, nozzle. Hopefully during testing I will be able to see a difference.

So with all the machining and welding done I ended up with a completely serviceable propane burner. At least it looks like a burner, I suspect it can’t officially be called one until it actually shoots a flame. For now the burner sits on the bench while I collect the propane regulator, bottle, and hook ups in order that I can feed it some hydrocarbons. I will work to post a continuation on the performance of the burner which will make up the first part for my future foundry.

I was able to get my hands on a 3 axis DRO (digital read out) for the RF-45 clone mill. I have never had any experience with these units however I have only ever heard good things about DROs on mills. I currently have some milling jobs in the brainstorm and early design queue so I figured I would take the time now to get the mill in peak running state.

The DRO system I obtained is a Chinabuilt SINO SDS6-3V 3 axis unit. I was able to obtain the user manual for the system before I decided to buy and had spent time determining if I would be capable of using the system. The manual translation is a bit rough and it takes some mental work to decifier what is being explained however I figured once I could get my hands on the system and work with it I was going to achieve success. The manual contains no installation instructions as these systems are a universal fit and therefore it relies on the ingenuity of the installer to ensure it is going to fit.

So this blog posting is nothing more then a documentation of pictures showing my installation. I had attempted to find pictures and information on how others have done the install however I had no luck. I decided that with nothing to go on I was going to wing it and see what I could come up with. I was very pleased with the install and I am not sure I would have done it any differently. I am sure there are other ways of doing it, and perhaps better ways, however at this point I will plead ignorance. I decided I would post some pictures in hopes that it will help others who are planning to perform an install. Perhaps the information found here will either show others what to, or not to, do.

The basic concept is that there are 3 linear scales that need to be mounted to the mill. One scale for each axis X, Y, and Z. The criteria for the mounting is as follows; 1. The scales cannot affect the operation of the machine in any way. They cannot be mounted in such a way that it limits adjustment knobs or travel. They also cannot impede machine maintenance such as lubrication points of the ways or gearbox oil changes. 2. They need to be mounted rigidly as to maintain the accuracy of the readout. The biggest challenge was the Z axis. 3. The scales need to be as protected as possible from any oil, coolant, or metal contamination.

So off I went to start drilling and tapping holes into the mills castings. The DRO came with a few universal aluminum brackets; I was only able to use one for the Y axis. I ended up having to fabricate a total of three other adapters to get all the scales mounted.

I’ll let the pictures tell the story. It took me approximately 4 evenings to do the complete install and in the end I think it was 4 evenings well spent. I am happy with the rigidity of all the scales. The Z axis scale, the one that gets exposed to the worst vibrations, seems to be holding fairly accurate. Since the install I have spent a few hours educating myself with all the math functions. The DRO is more then just a readout as it can also help to perform accurate machining functions such as circle drilling, radiusing corners, center finding, drilling evenly space holes along an oblique line, plus a whole range of other functions. I was able to successfully get my way through many of the functions. Perhaps I’ll save my new found knowledge for another posting.

The Y axis needed a bracket made to connect the scale to the supplied aluminum adapter. Using a chunk of scrap channel I milled a bracket to attach to the Y table.

These are the three completed brackets that I built for both the X and Z axis. I left the quill clamp in the picture to show how the aluminum adapter fastens. The rigidity of the Z axis bracket was a concern however the use of 3/8" aluminum plate seemed to do the trick.

I was able to neatly bolt the X scale onto the back of the compound table. The scale is out of the way and protected.

A complete picture of the Y axis was difficult to take. This is the top view of the Y scale bracket mounted to the Y table on the right side of the mill.

Here you can see the mounting of the Y scale on the left side of the machine. The factory aluminum bracket goes up and connects to my fabricated steel bracket. Rigidity is not a problem with the Y scale.

The 3/8" aluminum plate bolted to the quill clamp was the right choice. It looks clean and is out of the way. The angle cut towards the left rear of the bracket allows me to still drain the gearbox oil.

The Z scale was tucked in behind the vertical feed controls. It's mounting still allows me to access the nut required to angle the machines head.

The final picture is of the plate I built in order to mount the control panel arm to a wall stud.

 

The paint booth project progress continues to slowly take place. As usual I continue to be bombarded with side projects which always end up slowing down the main projects. The goal was to have the booth completed before the New Year. FAIL!!!!!! I figured out how to solve that problem, no longer set any goals. There we go…right back on schedule.

The main frame of the booth was previously finished. Before I can start to tarp the entire structure I needed to fabricate the intake air assembly. The plan is to create a pressure booth therefore a fan, and duct work, need to be mounted on the intake side. I had previously calculated out the air needs of the booth. Total booth volume is approximately 936 cubic feet. I want to ensure I can double the air exchange every minute meaning I need to find a fan capable of at least 1900 CFMs. My fan options open up since the fan will not be mounted on the exhaust side and therefore will not be exposed to combustible fumes. Unwanted explosions should not be too much of a factor. Of all the fan and motor assemblies I looked at none of them were perfect for my application. So I decided to build a fan assembly that would suit my specific need.

After flipping through pages of a local appliance parts supply catalog I was able to find a 22” 4 blade aluminum fan with a pitch of 27 degrees that was capable of producing 3640 CFMs of air movement. The horsepower requirement for the fan was rated at .37 horsepower with a max speed of 1420 RPM. I was able to find a surplus 1 horsepower treadmill motor with an RPM of 1750 for $20. This was going to work perfect. Since the rated fan CFM was overkill I would be able to pulley down the fan rotation to get the spec’d RPM. Once the paint booth is completed I will then be able to do further testing. If the CFM movement needs to be tweaked all I will need to do is re-pulley the system.

So I stated the ventilation portion off by welding up a collapsible aluminum frame to support both the fan and the duct work. The frame will fold in flat to the main frame in order to accommodate storage. The idea is that the fan assembly will need to be removed and stored separately from the main frame. With the frame built it was on to the fan assembly. Using some 11 gauge sheet metal a circle was cut and then lined with 1” ring rolled flat bar. With some spare aluminum and a couple of flange mount bearings I was able to fabricate a fan support. The treadmill motor has no case to it as it is designed to mount inside a treadmill assembly. Using some muffler clamps I was able to build a mount for the motor that allowed it to be suspended by its rubber end mounts. Hopefully having the whole assembly rubber mounted will reduce my main frame from rattling apart.

Since I am unsure of what final RPM I will be running I built the mount for the motor out of a length of angle iron. Since different pulley sizes will also impact my V-belt lengths having the extra bit of angle iron will allow me to customize my belt tension adjustment.

I have yet to build a shield for the fan blade. As it sits now I am sure it would do some serious damage to human body parts should something decide to get in its way. Before I finalize the fan assembly the rest of the booth will need to be completed and performance testing will be required.

Next step on the road to completion will involve having to secure a tarp to the main frame assembly. I am dreading this part simply because I am a one man operation that is going to be wrestling a 30’ x 40’ tarp over the skeleton and then having to trim it a fasten it. I suspect a calm demeanor and deep breathes will be involved.