Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines
Builds, Repairs, Show Your Machines! => Restorations => Topic started by: Paula on September 12, 2022, 01:38:07 pm
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Looks and runs great! Nothing that a few more BTUs of heat couldn't fix.
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Thanks for the nice comments, guys!
I'm happy with how this turned out, but there's no question that it could use a bit more heat. I was thinking about making a new aluminum heater plug to accommodate a third cartridge heater, but then it occurred to me that I could simply modify the existing plug to accommodate four heaters. My feeling is that the heaters need to be evenly spaced to provide uniform heat transfer to the boiler.
I drilled and reamed four new holes in the original plug as laid out below:
[attach=1]
The two original holes at the 3:00 and 9:00 o'clock positions would not be used. The wiring of the additional heaters proved to be the most challenging part of the job, given the limited space available. Here's how the finished installation looks before installing the bottom cover:
[attach=2]
With the four heaters wired in, the resistance now reads 23 ohms. At 120 volts, the heaters draw a total of 5.22 amps, and supply 626 watts of power. This is probably substantially more than the original heater put out, but I suspect that it's inaccurate to compare the heat supplied, per watt, for different types of heaters. While the cartridge heater is rated at 150 watts, I don't think that the full amount is transferred to the boiler. Not like a red hot nichrome element up-close-and-personal, only separated from the boiler sheath by a thin layer of mica.
At any rate, I proceeded to conduct a running test. I wanted to see what it was capable of, so I didn't hold back on the volts (it was connected to a variac.) I'm afraid it overwhelmed the poor windmill, eventually spewing water across the bench:
https://youtu.be/EIyIaQMvXUY
Looks like I need to make one of those little Baker fans. :D Around 90 volts would probably make for a more dignified steaming. I also need to try some heavier springs on the throttle and whistle valves. They seem to be leaking like sieves.
Anyway, thanks again for the kind words!
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Well done! Beautiful restoration.
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Fantastic restoration! I will be taking a similar approach to a heater replacement on an early Jensen engine in the near future.
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I'd say she is running pretty good and she looks good doing it! So darn shiny and new looking - fablous!
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Ok, let's wind this up...
Just before assembling the B31, I managed to get all the parts together in one place for a "group shot":
[attachimg=1]
Everything went together pretty easily. I installed the 2 cartridge heaters in the bottom of the boiler, using some boron nitride paste on the heaters and the plug. Here's what it looked like with the heaters installed:
[attachimg=2]
I cut out a piece of insulation for the bottom of the heater plug... :
[attachimg=3]
...and a thicker piece to go between the heaters and the bottom plate:
[attachimg=4]
Here are some pictures of the finished engine (I added a small pressure gauge at the last minute):
[attachimg=5]
[attachimg=6]
[attachimg=7]
As I suspected, the performance of the finished engine is not exactly overwhelming. It works, but it's kind of like me... only able to go flat out for less than a minute. :-\
Here's a short video of it pulling a modest load (for a modest amount of time!):
https://youtu.be/rS1XtWbZ3E8
I think this engine could definitely benefit from a third 150 watt cartridge heater. I haven't decided yet if I'm going to add a third heater, but I will most certainly use three heaters on any future applications of this type.
Thanks for watching! :D
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Lots of nice machining there Paula ,interesting approach to the burnt out/missing heaters for these units.
Wow - lookie there - who needs Chinese crap when you have an American Machinist! Sooooo jealous! I literally been day dreaming about equipment like that... though even if someone dropped one off on my driveway I wouldn't know how to operate it!
I am not surprised the two 150w guys didn't give you enough. I assume v2 of the heater is coming with 3 cartridge heaters? I am so excited to see that!
Thanks for the acknowledgement, guys! I suppose the question of what is "enough" is an open one. I will wait and see how this one performs under load before deciding. Going to a 3-heater design wouldn't be that difficult -- I already have an extra cartridge -- I would just need to make a 3-segment plug. We'll see how it goes. If she starts up and runs halfway decent, I may call it good enough. It's had a hard life, and maybe deserves an easy retirement! ;D (I know I do!)
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Wow - lookie there - who needs Chinese crap when you have an American Machinist! Sooooo jealous! I literally been day dreaming about equipment like that... though even if someone dropped one off on my driveway I wouldn't know how to operate it!
I am not surprised the two 150w guys didn't give you enough. I assume v2 of the heater is coming with 3 cartridge heaters? I am so excited to see that!
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Lots of nice machining there Paula ,interesting approach to the burnt out/missing heaters for these units.
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Replacing the Original Heater
In my day job, we frequently work with cartridge heaters, both for hot-melt glue application, and 3D printers. So, being somewhat familiar with their ins and outs, I decided to try cartridge heaters to replace the missing B31 heater unit. Mind you, this was long before the recent solutions had been worked out, namely improvising the 35MM Chinese band heater, or simply winding a new heater with nichrome wire, as pioneered by Junkologist (Mike). In my case, even with those approaches, I would have to come up with a way to hold the heater in place, since my engine didn't even have the internal expanding clamp.
Given all that, I went ahead with designing a cartridge heater solution. It turns out that cartridge heaters are not all that well-suited to this application. The only length that will fit is a 1" long heater, and the largest diameter in this length is 3/8 inches, which is rated at only 150 watts. If I used two of them (300 watts), this would be somewhat less than the 350 watts of the original heater. If I used three of the 150 watt heaters, I would be well above the original rating at 450 watts. I was a bit leery of exceeding the nameplate wattage, even if performance might suffer as a result. As it turned out, I wish I had went with the three heaters.
Here is one the heaters that I purchased. It's a Tutco #CH15766, rated at 150 watts, 120 volts:
[attachimg=1]
Due to the cramped quarters beneath the boiler, I would need to bend the heater's leads at a sharp right angle. To be able to see what I was doing, I decided to remove the factory-installed hi-temp sleeving. Here's what the heater looks like with the sleeving removed, and the heater wires bent:
[attachimg=2]
I used some PTFE heat-shrink tubing to re-insulate the heater wires where the bends were made. I then dressed the leads to length, and crimped some ring terminals to the wires. Here is the cartridge heater pair, ready for installation:
[attachimg=3]
For best performance and life, cartridge heaters should be installed in a close-fitting hole, preferably in a aluminum block which can conduct the heat efficiently to the target medium (in this case, the boiler sheath, and the water within.) I decided to make an aluminum plug to fit the I.D. of the opening in the bottom of the boiler. It would be split into two parts, each with a reamed hole for a heater cartridge. A set screw between the plug halves would force the two halves firmly against the sides of the opening.
Here is a what the plug looks like after turning to size on the lathe:
[attachimg=4]
A rear-mounted parting tool was used to cut off the plug:
[attachimg=5]
Reaming the drilled holes to size for the heaters:
[attachimg=6]
A set screw hole was tapped using a 5/16-18 taper tap:
[attachimg=7]
I clamped the plug to the bed of my cutoff saw to split it down the middle:
[attachimg=8]
Here is the finished plug assembly and heaters, ready for installation:
[attachimg=9]
(Stay tuned for more...)
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Thanks for the kind words. I've been doing this kind of work for a long time, so I've accumulated a lot of tricks and tools.
On the insulators, I've lately gotten away from the Garolite G-7 material, in favor of PTFE (Teflon). The G-7 material is brittle, weak, and abrasive, and has a maximum temperature of 425 degrees. The PTFE is non-brittle, abrasion resistant, machines beautifully, and has a max temp of 500 degrees. It's also good for making hi-temp seals, like sealing washers for boiler caps.
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@Paula , you do SUCH a better job than me, I haven't the proper tools or the patience. I love your little power insulators you make, I'd wished I could make those (saw that in a different posting of yours). And you idea on the "counterbore the mounting faces" what a great idea and you are spot on about the gaskets. I have gone though a number of different types and don't like any of them. I more or less have given up finding a perfect fit.
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Moving on...
Once the base and engine frame were blasted, I sprayed on several coats of hi-temp primer. When that dried, I wet-sanded down some of the high spots, and sprayed several coats of red engine paint. I used Rustoleum, since I had some left from the last project, though I'm not exactly in love with the stuff. It takes forever to dry, and loses some of its gloss over time. The shine can be brought back with polishing compound, but it shouldn't be that way. Will try the Krylon next time. Here's how the base turned out, after mounting the heater terminals, etc.:
[attachimg=1]
[attachimg=2]
Before painting the engine frame, I took the time to counterbore the mounting faces for the various steam connection points for o-rings. I like to do this just to eliminate hassling with gaskets, which often don't seal very well, and even if they do, if you take it apart, they may not seal when you put it back together. Here's what it looked like after painting:
[attachimg=3]
[attachimg=4]
While the base and frame were drying, I turned to cleaning and polishing the various parts as needed. The plating on this engine wasn't bad at all. A few worn spots here and there, but well into the "acceptable" range. Here is what the finished lot looked like before any polishing or painting:
[attachimg=5]
I wanted to make a new boiler sight glass, so I purchased some 1/4" O.D. borosilicate glass tubing off of eBay. I usually file a small notch with a triangular needle file where I need to break it, and it usually breaks pretty cleanly. If not, it can be trued up on the belt sander. Make sure the length is long enough to go well beyond where the seals will be, but not so long that you can't angle the tube into the fittings. I have found that 1/4" ID x 3/8" OD o-rings make a reliable seal for the 1/4" dia. tubing. You need at least 2 rings at each end to get sufficient sealing pressure:
[attachimg=6]
[attachimg=7]
I have found that the 2 threaded joints where the sight glass fitting attaches to the boiler are best sealed with Loctite 542 (It's a brownish liquid.) Be sure to let is set up for 24 hours before steaming.
(To be continued)
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After restoring the Quality Brand (Empire) B30 horizontal engine, I began to fancy a B31 vertical engine. Though different in configuration, these two models share many of the same parts. About a year ago, a nice B31 came up on eBay, and it appeared to be pretty much intact, requiring very little effort to make it like new:
[attachimg=1]
All the parts seemed to be there, even the normally busted-off whistle topper. The stack had a hole drilled through it, no doubt to insert a pin or rod for added torque when the thread seized. No matter, I already had a nice original to replace it with.
[attachimg=2]
I should have paid closer attention to the following picture, as it gave a clue as to a problem I would only discover later:
[attachimg=3]
Notice the dark discoloration towards the rear of the base? This should have been my cue to ask the seller to post a picture of the bottom of the engine. Trusting soul that I am, this didn't even occur to me. I figured that an engine that nice, should probably still have a working heater. Even so, the seller's description included the words, "Untested, no clue if complete, selling as is, no refunds." That didn't faze me none, and I proceeded to turn in the high bid.
Imagine my disappointment when I received the engine only to discover that it was completely naked below the base: no bottom cover, no heater, no heater clamp, no nothin'! The terminal pins were still there, as could be seen from the top side, but everything past that point was AWOL. I felt like an idiot for not having been more diligent about evaluating the engine's condition before bidding. I could have contacted the seller, and probably should have, but he was very clear in stating his terms of the sale. I doubt he had any clue about it either way. I needed to own my negligence, suck it up, and move on. Besides, I had an idea of how to solve the problem, and it could even turn out to be a fun challenge.
I disassembled the engine to begin the restoration process. You can see from this bottom view of the base, that the heater must have died a violent death:
[attachimg=4]
...though not as obvious from the top side:
[attachimg=5]
Nevertheless, the base got a good blasting to remove all traces of the heater's spectacular demise. I also blasted the engine frame:
[attachimg=6]
I needed to replace the missing bottom cover, so I cut a piece of stainless sheet metal to size and spotted and drilled a couple of holes for the screws:
[attachimg=7]
[attachimg=8]
So far, so good. Next: Paint for the base and engine frame. Stay tuned! :D
Paula