Sight-Feed Oilers

For the Thompson Type-Caster

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1. Thread Size

The Mold Stand Sight Feed Oiler, 54TC35, screws into the Mold Stand Sight Feed Oiler Elbow, 54TC36. This is a piece of pipe known as a "street elbow" (which is a female-to-male fitting; a regular elbow is female-to-female.) The Sight Feed Oilers on both of my machines were missing as acquired, but fortunately the Elbows were there. Their threads would appear to be 1/8 National Pipe Thread (NPT).

As an aside on pipe threads - I find them to be a bit weird and quite confusing. They're weird because they're tapered threads. They're confusing because their nominal sizes are nothing like their actual diameters. The nominal thread size (1/8 inch here) of an NPT thread is the internal diameter of the Nominal Pipe Size (NPS) Schedule 40 pipe for which the thread would be appropriate. So if you had an NPT thread on Schedule 40 pipe, it would have a nominal Internal Diameter of 1/8 inch. But because pipe wall thicknesses vary for different Schedules and different kinds of pipe, if you had an NPT 1/8 thread on some other kind of pipe it would have a different nominal Internal Diameter (but the same external dimensions, I believe). In any case, the upshot of this rather confusing system is that the measured diameter of an NPT thread is nowhere near the nominal size for any kind of pipe (even Schedule 40). The pipe outside diameter of a 1/8 NPT thread is 0.405 inches (and 27 threads per inch, which is also a bit weird).

So, we need a Sight Feed Oiler with a 1/8 NPT fitting.

2. Naming

The first problem in finding replacements is one of terminology. While Lanston calls this part a "Sight Feed Oiler," and while that is the traditional name for this object, and while it is even a pretty modern common name for this object, if you start searching catalog literature for this term you may not find it. There are just too many different kinds of "oilers," and the kind we want isn't always called an "oiler" at all.

3. LDI101-11 (Aluminum)

If you're searching McMaster-Carr, what you want to look for are "Adjustable-Flow Oil Reservoirs". Then look at the results for "Direct Mount." McMaster lists over a dozen, but only one of them has a thread which will fit my two Thompsons. This is their stock no. 1167K51 (for the glass bowl version; given the heat of the application I simply ignored the plastic bowl version). Capacity 5/8 oz, bowl diameter 1 1/2 inches, overall height 4 9/16 inches, and (most importantly) thread of 1/8 NPTF male. They're not cheap: $29.62 in early 2012.

What you actually receive in fulfillment of such an order is a part manufactured by LDI Industries ("LD" for Lube Devices) in Manitowoc, Wisconsin. They call these things "RESERVOIRS, DROP FEED PIPE THREAD NPTF (DRYSEAL)". The McMaster 1167K51 turns out to be their p/n RDF101-11: capacity 5/8 oz., bowl diameter 1.5, height overall 4.56, height up to the bowl 1.38, and thread 1/8 NPTF. It's made of aluminum, and the glass bowl version is rated to 250 deg. F. I'm not quite sure what determines the temperature rating, as the glass bowl is borosilicate glass (that is, generic Pyrex), which should be able to handle much more. They also have 1 oz, 2 1/2 oz, and 8 oz versions with 1/8 NPTF threads, but the 5/8 oz one is already almost too large for the Thompson.

They supply this with an NPTF thread. This is National Pipe Taper Fuel (not "fine"), also called Dryseal American National Standard Taper Pipe Thread; defined by ANSI B1.20.3. NPTF is basically NPT with altered thread profiles for an interference fit to prevent leaks. It works with the NPT thread on the Thompson, though.

The LDI Industries web page for this is: This is their Bulletin F797-1.

It's a lovely oiler:

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Here it is fitted to a Thompson. The only problem that this oiler presents is that because it is of a greater diameter than the original Thompson oiler, it interferes with the removal of the Mold Cap. This isn't a problem - when removing the Mold Cap, just rotate the Sight Feed Oiler Elbow about 30 degrees to the left so that it's out of the way.

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4. Essex OC33A0/00 (Brass)

An aluminum oiler is great, but would be nice to get one in brass.

Essex Brass (in Warren, Michigan, does list two brass sight feed oilers in the right size range. One of these definitely works with the Thompson (I've tried it); the other probably works as well.

There seem to be a couple of errors on their website, however (besides the images not loading). Both of the oilers in question have identical descriptions. One of these is in error. I called and spoke with Brian at Essex Brass, and he tells me that their No. 0 "Pilot Snap Lever Sight Feed Oiler" part No. OC33A0 (letter O C33A figure 0) has a 1 1/4 inch diameter glass and a 5/8 oz. capacity (this does match their website). He says that their No. 0 "Pilot Snap Lever Sight Feed Oiler" part No. OC33A00 is slightly smaller, with a 1 1/8 inch diameter glass and a 1/2 oz capacity. Both sell direct from Essex for $32.91 as I write this in early 2012. Brian told me that the two oilers were "the same" except for capacity, and that few people bothered with the smaller "00" unit.

I did, though, order the OC33A00 (the 1/2 oz unit). Here it is installed on Thompson s/n 12,492. It fits the machine perfectly. I have not yet run the machine with this oiler, so I don't know how well it works. It operates more stiffly than the LDI unit, but brass just looks better on the machine than aluminum.

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The advantage of the 1/2 oz. oiler is that it is of lesser diameter than the 5/8 oz unit. This means that it does not interfere with the removal of the Mold Cap.

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5. Lunkenheimer

It would appear that a successor to the former Lunkenheimer company of Cincinnati (famed not only for their oilers, but for valves, steam whistles, and all manner of lovely brass fittings for machinery) is still operating the old Lunkenheimer plant. The Cincinnati Valve Company has a website at and list no fewer than three models of sight-feed oilers (they call them "oil cups"; confusingly, they also call other things "oil cups" and yet other things "sight-feed valves"). The Lunkenheimer models are the "Royal," the "Sentinal," and the "Paragon." (The Essex Brass oiler above is very similar to the Lunkenheimer "Sentinal.") All three are listed in various sizes, including "No. 0" size, which is 5/8 oz. capacity with a 1/8 pipe thread shank. Download the "Engineered Specialties Full Catalog" (Bulletin ES8-94) from their website.

I have not yet investigated trying to purchase one of these oilers.

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