Author Topic: Jan Ridder's Glass-Cylinder Flame Eater Mk2  (Read 12558 times)

Offline bent

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Jan Ridder's Glass-Cylinder Flame Eater Mk2
« on: July 25, 2017, 06:57:17 PM »
Well, wish me luck.  This is engine project #3 for me, based on the engine shown here http://www.ridders.nu/Webpaginas/pagina_happer_inw_schuif_mk2_glascilinder/inw_schuif_glass_frameset.htm.  I emailed Jan from his website, and promptly received his drawing set for the subject engine.  Of several flame-eater (flame licker?) engines I looked at, I liked this design because it seems to eliminate any potential issues with lubrication, corrosion, and thermal expansion that all-metal designs might face.  Also, what the heck, I've never tried machining glass or graphite.  Jan's engines are so darn pretty, I think I may be embarrassed to show my version when its done...but I'm more of a function drives form kind of guy, so if it works and runs, I'll be happy.

So, first I've been slowly working through the plans and converting where necessary to US customary units (while I can find metric sized bearings and tubing, they are typically double the cost of near-sized inch equivalents) and threads that I have taps/dies for.

The first actual "machining" work I have done was on some McMaster-Carr 1" borosilicate (pyrex) glass tubing, and is more grinding than cutting.  Jan on his website shows how he built a cute wet diamond saw from a dremel tool.  But, I already own a cheap wet saw and have used it a lot cutting geodes, so gave it a try.  Made a quick little jig from polycarbonate to hold the tube perpendicular (first photo below), and used careful hand feeding...to make some really nasty looking cuts, heavy chipping (3 tubes shown in photo #2 below).  Methinks my tile saw diamond blade is a bit to coarse and/or wobbly (and lower speed? need to check that) to make good cuts on glass.  Also hand feeding is a bad idea, as over-feeding was definitely causing some if not all of the heavier chipping.  One of the best pieces I made was done with very careful, slow cutting, but still had some fairly large chips breaking off the edges.  I could probably sand down the edges to clean them up, but it will be a lot of work.  Will probably pursue a dremel blade and experiment some more.

Next, I checked the i.d. of the McMaster tube with calipers - and saw out-of-round and end-to-end variation of the i.d. of over .005".  Jan uses glass syringes for his cylinders, which have a very closely held precision-bore (+/-.01 mm or .0004") in order to keep the glass plunger of the syringe from sticking/binding.  This makes it much easier for him to get very tight fits with his graphite pistons.  Hm  :thinking:.  I looked for precision bore glass tubing, and while it's available it only comes in large lots for several hundred dollars per box of several dozen or so.  Unless a bunch of people here start doing these and would be willing to split the costs, I don't think that approach will work for me.  I also googled the patents for precision bore tubing, and found that they make it by vacuum-shrinking hot (softened) glass tube down onto precision-ground mandrels (no, spell checker, not mandrills, that would be cruel).  That's a neat trick, but I don't have a centerless grinder, vacuum pump, gun drill to machine the vacuum port, nor a oxy-fuel torch...but it would be a neat process to watch/perform.

So, more amazon shopping, and hey...managed to find some of the "Fortuna Optima" glass syringes in the right 20 cc size; these are the ones Jan recommends.  There also appear to be similar products for sale from Truth (with an umlaut on the u), made in India but have good reviews.  At $20 a pop, and one cylinder per syringe, this is spendier by far than the commercial-grade pyrex tube, and so am going to need to make up a good jig, and practice on the pieces of tube I've already cut before having a go at those.  Like I said, wish me luck!


Offline b.lindsey

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Re: Jan Ridder's Glass-Cylinder Flame Eater Mk2
« Reply #1 on: July 26, 2017, 12:59:18 AM »
So you are going to try and grind the ID's of the tubes to make them round like the syringe tubes? That should be interesting, as well as trying to polish them to clear again. Following along, good luck.

Bill

Offline Ian S C

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Re: Jan Ridder's Glass-Cylinder Flame Eater Mk2
« Reply #2 on: July 26, 2017, 10:08:26 AM »
Jan Ridders suggests that you may be able to lap the bore of a glass tube using diamond paste.
In USA there is a company called "Airpot" that makes glass cylinders with matching graphite pistons, these are made for door closers, but they were offering free samples, and they come in a very large range of sizes, from less than an inch up to about 4 inch (I think).  Worth thinking about, I think lapping glass tube could be frustrating to say the least.
Ian S C

Offline gerritv

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Re: Jan Ridder's Glass-Cylinder Flame Eater Mk2
« Reply #3 on: July 26, 2017, 02:54:26 PM »
I made a jig to use with Dremel diamond disc to cut the cylinders form my Mk2 Ridders gasoline engine. A dripping water tube kept things lubricated. A bit messy with the glass grit spinning to the back wall but excellent results.

Thankfully I can use an o-ring to seal the piston to glass, else I too would have been looking at lapping the glass interior.

Don't confuse activity with progress

Offline bent

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Re: Jan Ridder's Glass-Cylinder Flame Eater Mk2
« Reply #4 on: July 26, 2017, 06:19:07 PM »
Bill,
I thought about honing or grinding the commercial tubing to improve it, but have (since finding a source for the glass syringes) decided they are now just practice pieces to improve my cutting techniques and tooling before actually cutting the more expensive syringes to size. The chipping on the cut edges just doesn't make me happy, it may survive in an engine ok but I'd only see the chipped edges every time I looked at it.  Also, I have little confidence that I could create a honed/lapped bore as cylindrical and smooth as the precision-bore glass that I've seen and used for precision chem lab and rocket testing work (to make very precise sightglass flow/volume gauges), and is what I expect to see with the syringes when they arrive.

Ian,
I have one of the Airpot samples in about a 1/2" bore size, they are neat devices.  But the "fun" here is trying to actually make one of these.  Pretty sure, based on the airpot I have, that they are using precision-bore, i.e. "hot shrunk" glass tubing, as the bore is very smooth and clear, not like ground glass at all.

Gerrit,
I may go the Dremel route, just like Jan shows on his website and as you discussed.  A bit more tooling to build, but may be better to cut glass with as you can vary the wheel speed to get a smoother cut.  After researching things a bit, I found that the tile saw I have is a 5500 rpm nominal wheel speed for a 7" diameter disk, whereas the dremel is about a 1.5" disk at up to 20000 rpm; those numbers put the tile saw at twice the dremel capability in terms of rim speed on the wheel...maybe the tile saw is too high a sfpm, as Jan says he runs his dremel at about half of full speed?  Irregardless of which cutter, I need to control the depth of cut according to an email conversation with Mr. Ridder, a few thou per cut is what it sounds like.  So, to the shop this afternoon to whittle out a lead screw mechanism (cheap and sleazy, not pretty - this is a one shot device to test a theory, but will hopefully get the job done).

Offline Tennessee Whiskey

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Re: Jan Ridder's Glass-Cylinder Flame Eater Mk2
« Reply #5 on: July 26, 2017, 07:17:01 PM »
This may sound silly, but, I noticed several "bottle cutters " on eBay. Could something like this work for cutting the tubes

Cletus

Offline bent

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Re: Jan Ridder's Glass-Cylinder Flame Eater Mk2
« Reply #6 on: July 26, 2017, 10:27:21 PM »
Cletus,

You mean the kind that scratch a line with a sharp steel or carbide, and then you tap or bend the glass to break it?  Dunno, I thought about the scratch-and-snap method but thought my tubing would be too large of o.d., and thick walled to get a clean/square edge break.  I've snapped 1/4" glass tube before, but bigger stuff was always sawed.  The second problem, for the flame-eater, is that you need a slot in one end for the valve, you can see I was trying to make that slot with the tile saw, and while it cut ok, I got a lot of edge chipping on the inside.

Love your handle, by the way.

Offline Plani

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Re: Jan Ridder's Glass-Cylinder Flame Eater Mk2
« Reply #7 on: July 27, 2017, 09:36:45 AM »
I'll be following your build too.

For cutting off test tubes I'm using Dremel tool with a diamond disc too. What I found is, it's important to have a slow feed because most of the chipping occures when the cut comes through on the back side. I'm using then a torch to slightly melt the cut surface again so it won't crack.

Plani

Offline Ian S C

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Re: Jan Ridder's Glass-Cylinder Flame Eater Mk2
« Reply #8 on: July 27, 2017, 11:06:08 AM »
One chap I'v had contact with through the Stirling Engine Forum uses a dremel tool and diamond disc mounted on the tool post of his lathe, and clamps the tube (usually a test tube for a hot cap, and a smaller one for the displacer) in the chuck of the lathe.
This person is a school teacher in Belgium, and each year his class does a Stirling Engine as a project.
Ian S C

Offline bent

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Re: Jan Ridder's Glass-Cylinder Flame Eater Mk2
« Reply #9 on: July 27, 2017, 04:16:25 PM »
Plani, thanks for confirming my thoughts regarding fine feed control.  I modified my jig yesterday to put a screw feed on it, and the syringes I ordered should be on the brown truck tonight, so...maybe sometime next week I will get a chance to make some fine silica powder.  I'd say this weekend, but family matters will take priority.

Ian, I thought about that approach too, but two things have kept me from it so far - one is that most people recommend using a wet saw for glass to prevent chipping, and the second is not wanting to get silica dust all over my poor abused mini lathe.  Though it's a fallback method if the jig fails.

Offline Ian S C

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Re: Jan Ridder's Glass-Cylinder Flame Eater Mk2
« Reply #10 on: July 28, 2017, 03:00:20 AM »
I think he drips water over the tube as it cuts, and he also covers the lathe bed.
Ian S C

Offline bent

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Re: Jan Ridder's Glass-Cylinder Flame Eater Mk2
« Reply #11 on: July 28, 2017, 05:46:23 PM »
Ok, that makes sense.  Hm, a waterproof ways apron, and maybe a drip bucket...could work...may think about that some more.  Jan also suggested using turpentine as a substitute for water coolant, and I had thought of using automotive glycol, both would help reduce corrosion concerns on the lathe.

Offline bent

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Re: Jan Ridder's Glass-Cylinder Flame Eater Mk2
« Reply #12 on: August 09, 2017, 06:21:59 PM »
Well, I've learned some things.  The tile saw just doesn't make a clean cut, no matter the feed rate.  Quality of cut improved, but never approached the quality of the factory cuts, just too many big chips along the edges.

But got in some dremel-type diamond saw blades, and had a try - much better.  This method has a couple of advantages - the saw power is much lower so over-feeding is easily detected and corrected.  Also the grit used on the blades seems quite a bit finer than the tile saw - I tried a few dry cuts and collected the swarf produced on a paper towel, and the dremel blades produce a fine dust vs. chips/shards from the tile saw.

So, built up a "rig" to make wet cuts, see photos below.  The "drip can" is a typical tomato can repurposed.  Drilled a 3/16" hole and soldered a short length of brass tubing into it.  The tube was tapped 6-32 on one end, and a hacksaw cut made about 1/8" from the end.  Stuck a 6-32 ss cap screw into the the threads, and presto, a variable-drip rate valve (second photo).

In the third photo, I am using the tile saw base again, but with a dremel tool clamped to the table and braced against the tile saw blade.  The drip can filled with water sits atop the tile saw motor, and the screw adjusted to about 1-2 drops per second.  Dremel set to the slowest speed, and my custom-built screw-feed mechanism slowly advanced until the saw is just kissing the surface of the tube.  Rotate tube slowly thru a couple turns, advance the screw (1/4-20 thread, but turnning a big fat knob about 1/10 turn or less per step, so figure .002" typical cut).  The saw produces a clean, chipless cut on the o.d., but when the last .005" or so of  i.d. is being cut through, the edge tends to break away leaving a slightly chipped surface.  Not too bad, and should be easy to sand smooth with some wet/dry paper.

Fourth photo is a blurry pic (sorry, used the phone instead of my good camera) of the various practice cuts made.  The left tube top edge is factory-made, the middle is a dremel wet cut, and the left tube with the tile saw; you should be able to see the difference of the former two to the latter.

Fifth photo is a picture of what else I've been doing - squaring up and sizing the stock for the flywheel and piston supports, and base plate, after plasma cutting a big chunk of extruded 6061 Al (18" x 24" x .350 thk and warped/twisted pretty badly) down to manageable chunks.  Lots of swarf.  Should have taken pictures of the mill covered in chips, but I keep leaving my camera at home when at work, and at work when at home :old:

Last photo is a picture of one of two Fortuna Optima 20cc syringes, these are definitely worth the price.  I tried the Indian competitor syringe (Truth with an umlaut) and returned them as unusable - too much variance in the i.d. to form a consistent air-tight seal.  The Optima syringes can be held inverted, thumb sealing the outlet, and the plunger will not slip downwards; without sealing the outlet the plunger freely slides out.  Variation of the un-ground i.d. surface of the cylinder is less than .0002" on the diameter, using a bore mic with that precision.

So, tonight I will mark the tubes and start cutting.  And remember to take my good camera with me.


Offline Ye-Ole Steam Dude

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Re: Jan Ridder's Glass-Cylinder Flame Eater Mk2
« Reply #13 on: August 09, 2017, 09:35:19 PM »
Bent, a friend of mine used to make drinking glasses from wine bottles. She would make a "ring mark" with a glass cutter set in a wood fixture where it was to be parted. Then she would wrap a piece of cotton twine real tight along the groove/mark. Add some lighter fluid to the string, set it on fire and after (guessing) 30 seconds or so, tap it with a wood mallet. Slick as can be, the top would snap clean off. Then she would polish the edge on a wet wheel.

Don't know if that would work with your item?

Thomas
Thomas

Offline Plani

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Re: Jan Ridder's Glass-Cylinder Flame Eater Mk2
« Reply #14 on: August 09, 2017, 10:04:46 PM »
Bent, to me it looks like you have the glass cutting process prety much down  :ThumbsUp:
Good luck with the syringes!

Plani

 

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