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MG TD TF 1500 - Armolt Heater Rheostat Knob

I'm in the midst of restoring an Arnolt heater and I have what I believe to be all the parts, including the switch bracket and rheostat, but I'm missing the knob. From the period photos I've seen it appears to have been a white or tan "chicken head" style pointer knob which allowed the lamp bulb inside the rheostat's center shaft to glow through the knob (i.e. the light comes on and knob glows when the switch is on).

I've looked everywhere for a replacement knob to no avail. The problem is that the center shaft is quite thick and is keyed, unlike most 1/4" knurled shaft knobs out there.

Does anyone know of a source for an original-style knob? Failing that, can someone either loan me theirs to make a rubber mold casting of the knob? (Or, can they make a casting for me?) Rubber casting will not harm the knob in any way.
Kevin McLemore

Try Ben Cordsen, he restores them.
George Butz

Good idea. I got a label and bypass connector from him and he was very helpful and prompt.
Kevin McLemore

Ok, I contacted the very helpful and thoughtful Ben Cordsen. You know, I never cease to be amazed at what a great hobby this is, to have such wonderful folks involved! Sadly, though, Ben reports that he does not have a source for the knobs and has no old ones in stock, but he agrees they're rare as unicorn poop (my words!).

That being said, if I could get one as a sample I'm fairly certain I could cast some new ones out of resin. If anyone has one to loan please contact me via email... just use my first initial and last name and I'm on hotmail dot com. Thanks!
Kevin McLemore

Kevin, I have one that is just taking up space in a toolbox drawer at the moment. I now just use an ON/OFF switch. I'd be happy to LOAN it to you. Just send me your mailing address at the email address above. Bud
Bud Krueger

Thanks, Bud! Very generous of you, and yes, I will definitely get it back to you, undamaged. It will take about 2 weeks turn around, if that's ok. I'll email you later tonight.
Kevin McLemore

Got your email, Kevin. With luck, it'll be in the mail tomorrow. Bud
Bud Krueger

Kevin
You can do this?? Make a rubber cast of a knob?
While you are at it, can you make a mold of the TF windshield wiper knob? Many of us here would like this item.

Tom
'54 TF
T Norby

Thanks, Bud - much appreciated!

BTW, for those who are interested, here's a couple of movies of my now restored Arnolt heater. Works really nicely - just need to make a knob and I'm good to go!

Video 1 (walk around):

http://vidmg.photobucket.com/albums/v296/procolharum/52%20MGTD/854B6B62-67D3-4DB7-9C86-C1D95A77DD9B_1.mp4

Video 2 (running)

http://vidmg.photobucket.com/albums/v296/procolharum/52%20MGTD/DF6DFF25-509D-43CF-B9E7-402BCD08B1F0.mp4

Before restoration:

http://oi60.tinypic.com/hsmkch.jpg

http://oi57.tinypic.com/2lt3gj4.jpg

http://oi60.tinypic.com/hsmkch.jpg

After Restoration:




Kevin McLemore

Tom, I've made rubber molds of many things - I teach composite materials science - and it's an easy way to make a copy of nearly anything.

That being said, I will admit that this is my first try at making a knob. Making the mould is dead easy, of course, and won't harm the original. But I don't know how making the final product will go.

I plan to make several moulds with Bud's original knob and then I'll make at least one copy. I can't reproduce the knob using injection-moulded thermoplastic the way that the original was made, so I plan to use finely chopped fiberglass mixed with cream-coloured epoxy resin (thermoset) and make a poured knob using the rubber moulds.

As to making other knobs, let's see how this one goes first! :)
Kevin McLemore

Hmm... seems those video links are bad.

I really hate Photobucket. *sigh*

Here's a different site for them:

Walk around:

http://tinypic.com/r/2ee94bc/8

Bench Test:

http://tinypic.com/r/23kudrd/8
Kevin McLemore

Sometimes we luck out! I lucked out the other day when looking for door knobs for my early Smith heater. Who would think the two door pulls would be available by themselves. If you keep looking, it's amazing what you'll find. PJ



Paul S Jennings

Amazing, Paul! Where did you find them?

I have that same round Smiths heater in my 1949 Triumph. It puts out an amazing amount of heat.
Kevin McLemore

Kevin, you've made a beautiful restoration of your Arnolt heater. I imagine all your cars are in much the same condition. Great job!
Jim Merz

Thanks, Jim. I'm not sure all of my cars are as pretty as this turned out, but I appreciate the kind thoughts.

I suppose that, as with anything, it's all in the details... and I will admit to being a bit particular about them (perhaps to a fault!). For example, the screws used to assemble the unit are not painted - instead they were lightly bead blasted and then given a single coat of matte-finish clear to keep them looking new for quite some time. I was also very particular about the color... I found a bit of good paint inside the unit, buffed it up to get to the original tint under the oxidation, then used two different commercially available paints to match that as close as I reasonably could. I think it came out pretty close, maybe just a shade darker than the original.

I would like to give *major* credit to Ben Cordsen with whom I've been corresponding. Ben offered several tips and also provided me with the special pipe to connect it to the engine as well as the label for the front.
Kevin McLemore

Package is on it's way, Kevin. Should be there Friday. BTW, it contains two rheostats with knobs. I'll let you decide which is the real Arnolt knob. More details in an email. Bud
Bud Krueger

OK, thanks, Bud. Yeah, I think I know which one is the real thing, based on literature I've collected.
Kevin McLemore

Can someone confirm if the knob first from the right with the 8 raised bumps from an original Arnolt MG dash, is the same as you are discussing?

I have noted these on other Arnolt MG's as all being black.

Rod Brayshaw

Nope. The one that we are talking about is a light tan color. Somewhat translucent so that the indicator lamp shows when it's turned on. Bud
Bud Krueger

Another knob

Rod Brayshaw

Interesting, Rod. That appears to be one of the later Arnolt heaters with the stamped front, as opposed to the cast front that mine has. The bracket for the switch - and indeed the switch itself - seems to have changed considerably as well. Earlier heaters, like mine, had an l-shaped bracket that was screwed to the facia. Yours seems to have the later clamping-type bracket.
Kevin McLemore

Kevin, I got these from ebay! Listed under Jaguar parts, XK 120/150. PJ



Paul S Jennings

Cool, Paul. Now if you could only get them in that kinda-pink/tan colour they originally came! :)
Kevin McLemore

another view of the switch. These images were collected from the internet.

My heater is in bits so any information is welcome.

Rod Brayshaw

Kevin, As mine are disintegrating, I'm just happy to get them at all! PJ
Paul S Jennings

is this how the brackets are used?

Rod Brayshaw

Indeed, Paul - any port in a storm!

And Rod, yes, that's exactly how it gets assembled. The black bracket has a slot in it that slips over the flange on the bulkhead and the extended bit has a bolt, shown in your photo, that then goes through the bottom of the battery box and it also clamps the angled support tube. The wood block in the battery box needs to be hollowed out a bit to allow for the bold head. I should note that the support tube only goes one way - if it's inverted the angles of the ends won't be correct. It's also important that the bracket be pushed fully home on the bulkhead flange to that there's no room for movement - remember, this whole lot is hanging by one bolt!
Kevin McLemore

See http://www.ttalk.info/Tech/Arnolt.htm for a bit on the mounting. Bud
Bud Krueger

My car has a KL heater so the knob is obviously different to the Arnolt. I attach a photo showing where my switch is fitted. I don't know if it was a factory fit or a previous owner but it looks great and matches the indicator switch in the opposite corner perfectly.

Jan T

J Targosz

Hi Kevin, I have just renovated the Arnold heater like you have. The plumbing seems different to the illustrations, my take off is at the back of the cylinder head where a tap has been fitted to the oblong plate there, but I have not got the by-pass hose additions, where did you obtain yours or did it come with the heater kit? that is all I am waiting for as I will have to obtain a modern rheostat switch and hide it.
Regards Adrian Wells TD 0845 TA 2870
Thomas WELLS

Hi Thomas (or is it Adrian?) - from what I understand the plate at the back of the head is not how the Arnolt kit was designed and supplied, though certainly there are are a great many that are currently fitted that way, and I'm told successfully so. That being said, the correct and original fitting involves a replacement tube for the upper bypas tube and Ben Cordsen can supply them for you for around $40. I got mine from him and they are well made and promptly shipped... Ben is a wonderfully helpful resource for these units, both with regard to parts and knowledge. He may be contacted at by using the ID "sculptart" within the hotmail dot c0m domain.
Kevin McLemore

This is a photo I found of the original Arnolt method for fitting it all up.

See here for more:

http://www.ttalk.info/Tech/Arnolt.htm

Kevin McLemore

As to the switch you require, might I suggest one like that shown below. They are available from a number of sources but you want to be sure the one you select is one that's for 12 volts and is lighted (the same switch comes in both 6 volt and unlighted versions). Here is the least expensive source I found so far for this switch:

http://www.americanclassic.com/asp/dyncatv2.asp?which=amclsall&p1=initial&p2=Heating%20and%20Air%20Conditioning%20Items&iyear=1954&ytype=to&exyear=1954

You would want part # EL118 on that page at $18.88.

This is the closest I've found to what I've seen supplied in the original kits, and at the very least it looks the part in terms of being period correct.

Kevin McLemore

Sorry, the link I posted for the switch seems to fail once it gets to their online catalog. Use this link and then choose to go to the online catalog for ordering if you wish.

http://www.americanclassic.com/Google_Base_HTML_Pages/EL118-1954.htm
Kevin McLemore

Kevin,

I would love to learn more from you on the casting of plastic parts. I have the mold but can not get to the desired outcome.

Thanks,

Sherwood
S Parker

Well, Sherwood, this is the first time I'm doing a knob, so I may be in the same place as you, in terms of experience! I've cast many other plastic parts, however, and it's really not that difficult. I'm just hoping I can get one that's strong enough - that little key in the hole has to take a lot of stress.
Kevin McLemore

Is this the knob being discussed? I had never realized that there was a bulb socket inside.
JKB

J K Barter

inside

J K Barter

Yes, JKB, that's the one. I believe that to be the originally supplied knob for the early Arnolt kits.

The bulb inside is a bayonet-style bulb, 12v, and will start out bright and dim as you lower the speed of the blower.
Kevin McLemore

Kevin, I'm reactivating this thread with a couple of questions,
1) Is that an original mount for the Arnolt switch that you show sitting on top of the heater? It looks great and very retro.
Any chance you could take some better pictures of it and measurements? As I am sure that they are not available anywhere, I'll see if I can make one up to match. I can probably rout one out of wood and then make a mold of that, a cast plastic copy would be better than nothing.
My current switch appears to be a two-stage control rheostat (pull out it clicks into two positions). Unlighted, I believe and probably not functional.
In the attached photo you can see the switch (black knob to the right on the aluminum bracket under the dash). The heater install was probably an "aftermarket" version and may have been installed ten or twenty years later. Early sixties maybe?
Does anyone else have a similar switch? Just curious.
Anyway, I really drool after your switch mount, Kevin. Very cool.


Geoffrey M Baker

1) Is that an original mount for the Arnolt switch that you show sitting on top of the heater?

-- Yes, it is. It's stamped metal. I'd imagine it wouldn't be too hard to make one up out of fiberglass or something.

Any chance you could take some better pictures of it and measurements?

-- I'll take some measurements and do a few photos for you later today.

As I am sure that they are not available anywhere, I'll see if I can make one up to match.

-- Actually, I see similar mounts come up on ebay once and a while... might want to keep an eye out.

My current switch appears to be a two-stage control rheostat (pull out it clicks into two positions). Unlighted, I believe and probably not functional.

-- The correct lighted-style switch is still available new... see earlier in this thread.
kmclemore

OK, here's the measurements...

The vertical bit is 1.5"
The horizontal bit is 2.25"
The overall width is 1.75"

Here's a couple of pictures.

kmclemore

Second photo...

Still working on making reproduction knobs... I've borrowed a couple from a nice member and I feel awful having held them as long as I have... I really need to get back to this and get it done! Sadly, between health, work and volunteer things I'm *way* behind on things. *sigh*

kmclemore

BTW, there's a really nice ARK-LES switch (period correct) for a vintage heater on eBay now... looks great!

www.ebay.com/itm/NOS-IN-BOX-1930s-1950s-DELUXE-ARK-LES-HEATER-SWITCH-BULB-LIGHTED-1932-FORD-/371235076979

(insert usual disclaimer... I have no relationship to the seller and cannot vouch for quality, etc.)



kmclemore

This thread was discussed between 15/09/2014 and 01/02/2015

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