V2: The Ceramic IPR

For the original version, click here

Background:

In August of 2004, frustrated at the high cost of commercial IPRs, I cobbled together a home-made unit using a quartz heater and some miscellaneous hardware. I wrote up a small page outlining my experiments for the benefit of other old house restorers out there. The response was unexpected. It seems there are many of you out there who like to tinker, save $, and DIY. As people began to share their own creations, I expanded the page and hopefully, provided you with a plethora of ideas from our IPR-building community.

Now it is time for Version 2 of the IPR. Having traded my original scratch-built quartz unit for a Herbeau fireclay sink, and in need of an IPR, I elected to investigate a new and promising modality of paint removal: ceramic infrared.

Theory:

The new unit would be a departure from the old. This new unit would be based on a ceramic emitter rather than your grandfather's quartz tubes of yesteryear. Why ceramic? One reason is that a ceramic unit would be easier to build with fewer parts. Commercial ceramic emitters are readily available. Efficiencies for ceramic emitters run from 85 to 96% whereas quartz ran around 60%. Therefore, a higher percentage of the energy supplied to the unit would be transmitted as infrared rather than light. Quartz rods tend to have infrared hotspots. Cermaic on the other hand, produces a more evenly distributed heat.

Thus my intention to build a new, ceramic based, IPR for the same or less money.

The Unit:

Anyway, yet again, this is the time to point out some safety issues and make a disclaimer. Making your own IPR involves electricity. The project involves wiring as well as drilling, sanding, and cutting. (jeez doesn't sound too bad) I am not advocating that you run out and build one, I am presenting my method here for your review. If you do make one, you do so of your own accord. If you electrocute yourself, or burn your house down, well, hey, that's life, and your own responsibility. I am comfortable with the potential hazards. You may not be, and I urge that if you should make one anyway, you proceed with safety in mind and a good dose of common sense.

Construction:

The first step was to order the ceramic emitter and gather some of the other parts that would be required to get this show on the road. The emitter I selected was a Salamander FTE module. This particular model (FTE-120-1000) is specified to operate at 120 volts. The emitter is manufactured by Mor Electric and can be purchased on their website.

Conveniently, Mor also offers reflectors and housings designed to fit their ceramic emitters. These housings are designed to be affixed to some stationary object like a wall or inner oven surface. With a little finagling, we will convert it to our use. Shown below is the housing/reflector as it arrived from Mor. The reflector is in the center and is of polished stainless steel. The housing is made of extruded aluminum.

The housing and reflector are shaped and designed for the element shown above. You can see that the housing has a ceramic terminal block installed. This makes it very easy to wire the element to house voltage. The cap plate for the housing is seen at the top of the image. This plate has grooves which slide onto the housing, covering the ceramic terminal block and wiring. All is held together by the end plates (steel). One end plate is seen at the left of the image above, the other end plate is affixed to the housing. To help visualize it, here is an end view with the reflector installed into the housing:

Confused about how it all goes together? Don't be. Let's take it apart and start putting the pieces together in sequence. We have paint to strip. The first step is to install the ceramic emitter into the reflector. Shown below, is the backside of the ceramic emitter poking through the hole in the reflector. The hole of the reflector is designed to accept the "knob" of the emitter. The knob has the two leads poking out of it. The knob also has grooves which allow it to be clipped in place using the supplied clip.

The clip is the only mechanical fastener for the emitter. It is sufficient to hold it securely in place. Any blunt trauma to the unit great enough to dislodge the clip, would likely break the emitter first. The leads emanating from the emitter are part of the emitter itself. They cannot be removed. They are metal wire encased in small interlocking ceramic insulators. Be careful with these. It you bust one off then you'll be breakin' out that Mastercard to order another emitter. Shown below, the assembly is simply turned over, so you can see the front.

OK, we're going to set aside the emitter/reflector assembly for a moment to concentrate on preparing the housing. The image below shows the housing flipped over, and a thin bed of fiberglass insulation is placed in the bay which will receive the reflector. I grabbed a handful from a roll of R13 wall insulation I had lying around. The housing has two holes for the leads. The insulation is cleared from covering these holes using the point of a pencil.

We've now hit the meat and potatoes of the assembly operation. The reflector/emitter assembly is inserted into the housing. This can only be done one way. The leads from the emitter are first gently pushed through the holes in the housing. Then, the reflector's studs are inserted into the housing's holes. Two nuts (supplied) are placed on the studs to secure the two assemblies together. In the image below I am tightening these with a nut driver.

Now we can turn the unit upright and begin to work on the electricals. Shown below, the emitter leads are secured into one side of the ceramic terminal block. You can see the two nuts holding the reflector assembly into the housing. You can also see that one end plate is affixed (the housing/reflector comes assembled, I never removed it). You can also see the green ground lug next to the terminal block. This will come into play in a moment.

Next we remove the one end-plate from the assembly, and modify it along with the other end plate. First we are going to install a grommet in the end plate that will hold the power cord. The first two images below show the grommet before and after installation. The plates come from the factory with the holes as shown in the first two images below. The large hole holds a 3/4" ID grommet very nicely. Only the power cord plate is fitted with a grommet. The other plate is left as is. "Height adjusters" are the projections that keep the IPR sufficiently away from the wood being worked on. For this design, I elected to place these on the ends of the unit rather than along the sides, as is traditionally done. I opted to do this because it is easier to place them on the ends rather than work them into the angles of the housing. We'll get into the height adjusters more in a bit, but for now, we must prepare the mountings for them on the end-plates. The three images on the right below show the end plates being drilled for two screws which will hold the height adjusters.

The last image above shows 3/4" screws with nuts placed into the new holes and tightened.

Let's prepare the power cord. Mine is a medium duty from Home Cheepo. You must use a medium or heavy duty cord that includes a ground wire. Grab it by the neck, hold it down on the bench, and cut the head off. Don't hesitate or you'll get that twinge of guilt so common when ruining a good extension cord. Separate the wires and strip 3/8" off each one.

Below I am dry-fitting the end-plate without the grommet. This one goes on the end away from the terminal block. I removed it again shortly thereafter. The screw studs face outwards.

Next we take the grommeted end-plate and thread the power cord through it. Then we affix the power cord to the housing using an insulated wire clamp. We secure the black and white wires to the terminal block. White and black can go in either connector. The green ground lead is then secured to the green ground screw. Try to arrange the wires so that they contact the housing as little as possible. The housing gets very hot, and I am concerned about the AC wires touching the housing. I intend to sheath the wires in teflon tubing and will update this section when I do.

At this point you might be wondering where the power switch is. I've elected to eliminate the power switch. The unit is turned on or off by plugging it in. This approach has several key advantages: there is no chance the unit will be accidentally turned on; there is no voltage at the unit when it's off; one less part to buy. As for a fuse, I'm investigating ways to implement it into the power cord. In the mean time, I always make sure that the AC outlet is properly grounded. I never assume. A three dollar outlet tester from Home Depot does the trick. As with the quartz based IPR, the primary safety net is grounding the chassis and ensuring that the AC outlet used is properly grounded. The secondary safety nets are a fuse and the handle. Local fuses tend to be used to protect appliances. This 'appliance' doesn't really have any components to protect but it's nice to know it's there in case the ground fails and/or the house circuit breaker is slow to act. Thirdly, as you'll see below, in case all else fails, the handle is made from a non-conducting material (wood).

It's time to slide the aluminum cover "cap-plate" on. This cover has internal channels that engage the edges of the housing. Slide it all the way on.

Now we can install the handle. The image below shows the two factory supplied mounting studs with their cam nuts. One is shown slid into the housing cover:

In order to elevate our handle off the housing, the studs will have to be a bit longer. I cut two studs from 1/4-20 threaded rod. Each stud is 3.25". Shown below, the old and the new, both are shown threaded into the cam nuts, with some washers and nuts thrown in for good measure.

Also shown above is the handle. It is a piece of oak dowel, 1.25" diameter. It is cut to 10" long to match the length of the housing. Here the holes are drilled in the handle using a jig (sorry, no drillpress). A small bit is used first for accuracy, then a bit slightly larger than the studs is run through.

Next, sleeves are made to cover the studs. They are made from half inch hollow aluminum rod, from where else, Home Depot. Each is 1.25" long. A quick swipe with sandpaper removes any burrs from the hack saw. While these are not strictly required, they add a certain je ne sais quoi to the finished unit, and will hide the only visible vestige of DIY.

Here the steps for installing the handle hardware: Washer on stud, sleeve, washer, handle, washer, acorn nut. Also shown in these images, left to right:

At this point I can mention that the lengths of the studs and sleeves were selected to keep my knuckles from touching the housing when I hold the unit. It's very important that your knuckles don't touch, as the unit gets very hot. If you have super huge hands you may want to test clearance first. Make the studs longer if required. The tradeoff is that with longer studs, it can be more tiring holding the unit in certain orientations. The remaining end-plate is now attached:

All that's left is the height adjusters. These I made from some 1.25" aluminum left over from the previous IPR. I cut each to 7.5 inches long, and drilled holes to match the studs on the end-plates. I rounded over all edges and corners so that these would not scratch any wood work. These are affixed with wing nuts so that they can be removed if necessary. Like the previous IPR, the height is not adjustable. I never found any need to adjust height once the proper height is found. The first image below shows the adjusters and wing nuts:

To be honest, I prefer not to install them. They do add weight (even if just a little). I do suggest you do keep them installed though; they have the very important benefit of ensuring that the unit is not accidentally placed face down on a surface where it would more than likely start a fire if left unattended. With the 'adjusters' in place, and more specifically with these adjuster on the ends of the unit, it is almost impossible to place the unit any way except on its side. (If you really try hard you can balance it face down on its adjusters, but if you round off the ends of the adjusters even this will be impossible)

Parts/Cost:

Required parts:
-1000W ceramic element: $31.25*
-Extruded aluminum housing: $55.20
Total: $86.45

Scroungable Parts (Home Depot prices shown):
-Quarter-20 Threaded Rod: $1.47
-9 foot medium duty extension cord: $9.87
-Grommets: $1.75
-#10 screws, nuts, wing nuts: $2.94
-Insulated cord clamp: $1.25
-Oak dowel 1.25"x36": $6.49
-Aluminum Sleeve: $4.38
Total: $28.15

*750 Watt element would be the same price

Performance/Caveats/Suggestions/Notes:

The ceramic element requires about ten minutes to heat up. When fully heated, the red logo on the element turns black. This unit throws off some serious infrared radiation. Paint sees this thing coming and jumps off the wood in fear. I will add action photos soon.

Caution: the housing gets too hot to touch. Do not touch it when operating the IPR.

There some improvements to be made and concerns about the design. These are things I am working on:

1. The unit gets very hot, and while I have no concerns about the housing and element, I am concerned about the cord wiring. This is why, as I mentioned above, I intend to sheath the cord wires in Teflon tubing. Inspection of the unit after operation has not shown any melted wire insulation, but hours on this IPR are still low. I do not know what the temperature rating of the extension cord wire is. More study required. Also, after each use, I open the cover and inspect the wires. If you make one of these, you should too.

2. The infrared output of this thing is phenomenal. The 1000 watt element I am using almost seems too much. The height adjusters could actually be longer than 7.5 inches. Using a variac, I will lower the operating power, and see if performance suffers. I suspect I might go with a 750 Watt element from the supplier rather than the 1000 Watt I am using now.

3. The unit weighs 3 lbs. 8 oz. This is a little too much. A weight loss reduction program might include replacing the steel end-plates with home cut aluminum ones. A series of holes could also be drilled in the housing itself. Enough holes would lessen the weight and perhaps vent the heat better.

I hope you enjoyed my second experiment. This page is somewhat preliminary and I will update as I learn and tinker.

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Page Updates:

20-Jul-07: Initial page published