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Assembling the Rajkumar oil expeller

Expeller screwThe assembly instructions that came with our Rajkumar oil expeller left a lot to be desired, but I figured it out pretty easily by looking at the picture below, snagged from their website

Rajkumar oil expeller

To be fair, it's possible that the hand-lettered CD that came with the expeller might have included more pictorial instructions, but I couldn't open the files on my computer.  In case you follow my lead and buy the Rajkumar expeller, I've included step by step assembly instructions below.

Your expeller will come partially assembled, but you have to remove the expeller screw and wash it, along with the rest of the expeller, prior to the first use.  Once the parts are Inserting the screw in the expeller barrelclean and dry, slip one of the two included washers over the handle end of the expeller screw and grease it with cooking oil, as shown above on the right.  The instructions note "This washer is exposed to very high pressure and should always be well greased."

Next, slide the expeller screw into the press cage (the main part of the expeller) until the smooth end pops out the other side. 

Putting the handle on the Rajkumar oil expellerThe handle slides right over the end of the expeller screw --- just be sure to line up the holes.  The longest bolt in the kit seems to be the only one that fits to put these two parts together.

Attach the handle with the longest screw

Screw the cap on the other end of the expeller cageThe cap screws easily onto the other end of the press cage.  Depending on the type of seed you will be processing, you may also need to screw the adjustment bolt into the cap.  We left the bolt off since we'll be expelling sunflower seeds first.

Those of you following along at home may have realized by now that, up until this point, the Rajkumar expeller is completely identical to the Piteba model, except for the bigger stand bolted to the back.  A Adding the oil funnel to the expellerclose look at both websites makes me pretty sure that the two brands are in fact identical, but that the Rajkumar expeller has added in the bigger stand and three handy funnels.  These funnels are made of much less strong material than the angle iron and heavy pipes that make up the main body of the expeller, but I'm sure they will hold up well under the light use they'll be put to.

The longest funnel (shown above) is meant to channel the oil away from the expeller so that you can collect your product in a larger jar than you could with the Piteba expeller.  The oil funnel is attached with a single screw threaded through the back of the expeller.

Seed cake funnelIf you're smarter than I was, you'll rubber-band your bottle of lamp oil to the rounded part of the expeller before moving on to the next step, but I didn't have any lamp oil on hand, so I went ahead and screwed the seed cake funnel to the front of the expeller with the other small screw.  I'll have to remove this funnel and attach the "lamp" before operating the expeller.

Assembled Rajkumar oil expellerTo complete assembly of the oil expeller, I popped the round funnel on the top, having to bend the base a bit so that it slid on smoothly.  This last photo shows the completely assembled expeller, with the lamp bottle in place to show its location.

Despite this long post, assembling the Rajkumar oil expeller only took about 15 minutes, and that includes a bit of head-scratching.  The kit came with absolutely everything you might need, too, including a tiny screwdriver and wrench.  I would say that assembly is within the reach of even the beginner DIYer.

Our homemade chicken waterer kit comes with even clearer instructions, helping you make your unique waterer in an hour or less.

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Give olive oil a try in the heater. How well it works will depend on the wick and the distance from the oil level to the flame. A relatively open wick works best, I think.
Comment by Roland_Smith Tue Oct 12 10:38:56 2010
That's a good idea! I think we're going to try kerosene first, though. Daddy explained to me that kerosene and lamp oil are pretty much the same thing, and we always have some kerosene in the barn as a heat backup.
Comment by anna Tue Oct 12 13:15:14 2010
I never knew there was another brand of oil extractors. I only knew of the Piteba. I will have to look this one up. I have thinking of getting one for a while now.
Comment by Jane Tue Oct 12 13:17:13 2010
The Piteba is a bit cheaper, but I think the extra funnels and hefty stand are worth the $16 difference.
Comment by anna Tue Oct 12 15:56:26 2010

I've got this oil lamp that used to run on kerosene / lamp oil. I stopped using it indoors because of the strong smell. Hopefully your sunflower seed oil doesn't come out tasting like kerosene! I'm searching for a wick that works properly with olive oil, but haven't found it yet.

Be careful with the expeller screw. It looks like it is the hardest to make and most expensive part of the whole device. I expect it to be designed so that the bolt locking the handle to the screw shears off before the screw itself comes to harm if you overstress it. Don't be tempted to replace the bolt with a higher grade one or fit a bigger handle.

Is there a small radius where the thin part of the screw meets the thick part? (where you put the washer on) If not, that is a place where it could to break because of stress concentration. Additionally I don't think you should lean on the lever because that would impart a bending moment as well as a torque on the axis.

Comment by Roland_Smith Tue Oct 12 17:20:33 2010

I'll definitely just do a short test run with the kerosene --- if it gives any flavor to the oil, that's a deal breaker. I have read that the impurities in kerosene make it smoke more, so I might have to hunt down some real lamp oil.

Thanks for those tips about the expeller screw! It shoulds like I'll have to be very careful. Mark was talking about maybe trying to hook an electric motor up to it to crank out more oil if we ever need a bigger quantity, but that might be a bad idea given what you've said.

I'm not sure I quite understand what you're asking when you ask "Is there a small radius where the thin part of the screw meets the thick part?" What do you mean by a small radius?

Comment by anna Tue Oct 12 19:16:34 2010

Standard simple design practice would be to take the maximum expected static load, multiply that by three, and design so that all parts just can handle that load. I do not know what the maximum resistance of the nuts in the screw would be, but IMO the worst case would be a jammed screw where you would have a person leaning with his full weight on the handle which would be in a horizontal position. So a cautious designer would design for three times that load, people being what they are. Now I haven't done the math, but it doesn't look that sturdy to me. But I could be wrong.

OTOH, they could have sized the bolt that connects the handle end to the handle to shear off before the expensive screw can be damaged. That's what us engineers call a controlled failure mode.

You could put on a electric motor drive, but you'd have to think that through. If the motor can generate much more torque and power than a human (which most easily can) you could break the expeller. Or the motor, depending on which type you'd use. :-)

Where the face on the screw that the lubricated washer sits on (your top-right picture) meets the handle end of the screw, there should be a small fillet between the face and the handle end.

The reason for that is found in solid mechanics. When you are turning the screw you are applying both a torque and a bending moment to the handle end. Now for both torque and bending loads, the stresses that these cause in the material of the screw are greatest at the surface of the material. Now where the handle end meets the thicker part of the screw, the stresses "flow" from the handle end into the thick part. Because these stresses have to go around a corner, they tend to concentrate themselves. And the sharper the corner, the bigger the concentration. If the concentrated stres becomes higher than the proportional limit of the steel it will yield. Wether that results in a bent shaft or a broken one depends on the kind of steel used and the treatment it has had.

So the fillet serves to reduce stress concentrations.

Normally food processing equipment is made exlusively from stainless steel since it is corrosion resistent and has antibacterial properties. The screw looks like it might be stainless, but it might also be simply chrome plated. The rest of the machine probably isn't since it has been painted, and the tread on the end of the press cage looks like an oxidised brown color in your pictures.

IIRC, vegetable oils are made up of weak acids, which might corrode the non-stainless parts of the machine over time even though it will not rust because of the oil. I'm curious as to how the oil will taste and how the machine will hold up.

Comment by Roland_Smith Wed Oct 13 06:49:22 2010
I'll have to take a good, long look at that when I take the expeller apart again. Thank you for the extended explanation --- it makes a lot of sense now! It's always very good to know what not to do with new tools.
Comment by anna Wed Oct 13 17:29:01 2010
where can i get these hand operated oil expellers ?
Comment by Anonymous Fri Oct 15 06:42:11 2010
You order this one directly from India through their website at You might check out my previous post at --- the experience is very interesting, but if you have patience, your expeller will show up!
Comment by anna Fri Oct 15 08:39:24 2010
The Rajkumar is an copied from the Piteba oil expeller.
Comment by gpb Thu Nov 25 08:45:57 2010
Oops, I deleted GPB's second comment as spam since it just had a URL, then I saw this comment. You can buy the Piteba version (which does seem to be nearly identical except for lacking a bit of the extra frame on this one) at I haven't done a side by side comparison, but my gut feeling is that you get a bit more for your money with the Rajukmar, even though it comes to $10 more once you factor in shipping.
Comment by anna Thu Nov 25 09:41:13 2010
I went with the Piteba. The only difference is the lack of the funnel and oil ramp. Piteba made its oil press so that you can make your own funnel out of any size water or pop bottle. The oil ramp is just unnessasary it seems,. Its the original design and its made in Holland. Europe has better standards for employee pay, and metals and paints used in food equiptment. Seems extreme but I really shy away from metal food items made in India, China etc. I got mine on Amazon
Comment by marla Mon Oct 24 22:56:51 2011
You've got an excellent point about the standards for employee pay and worries about food grade paint. I guess things have changed in the last year if oil expellers are now available on Amazon!
Comment by anna Tue Oct 25 12:33:37 2011

I was looking into purchasing 1 maybe 2 of these expellers and I was just wondering how yours is holding up and if you have been happy with it

thanks for your help

Comment by Tammy Thu May 24 05:57:50 2012

Tammy --- I'm ashamed to say, we've only used it a few times. We were very unhappy with the smoky result from using kerosene to heat the expeller. Since we don't have a source for quality (ie non-smoky) lamp oil locally, Mark has tried some electric heating options, but no good results yet.

Keep in mind this is all due to us not following manufacturer's instructions, though! If you have a place to buy lamp oil near you, you might have better results.

Comment by anna Thu May 24 17:26:44 2012
I use the ultra pure lamp oil from Ace Hardware, you can also buy it on Amazon. I used our piteba for years in Hawaii making a great deal of Macnut oil. I have never had any aspect of it break down.
Comment by Derek Tue Jun 19 16:49:59 2012
Derek --- Thanks for the source on lamp oil! We do have an Ace Hardware about an hour away --- we'll have to try them the next time we're in the big city. Or look on Amazon.
Comment by anna Tue Jun 19 17:02:09 2012

you can also order the oil on Ace Hardware's website and have it shipped to your home pretty reasonable.

Remember to go through shop at home to earn a percentage back on your purchase

Comment by Tammy Tue Jun 19 18:29:44 2012

I was hoping that you have gotten your ultra pure smokeless lamp oil from amazon and hooked up a motor. It's fun to see the guys running their cars on this biodiesel, power to the mighty plants!

first off, I agree that European standards are more to my liking. Besides that, I am very aware that piteba is the guy who developed the idea. He is kind enough to share it with those who need it. I am sure that I want to support him and I believe that he is the one who evolves this project.

I am interested in putting a motor on mine. I could also put a bicycle sprocket on it and get some exercise!

Mark, before you retire this project, try the black sesame oil. Oh man. I love it so much that I want to just live on it, why not do that easily?

I would love any help you might offer about motorizing it. I am using a bicycle chain drive and a treadmill motor but I haven't gotten it together yet

Comment by Maryann Fri Oct 11 01:14:05 2013

Using Oil Expellers Manufactured by Gobind Expeller Company. Quite easy to install and good performance.

Comment by Anonymous Wed Mar 18 07:35:16 2015

One very unique homestead, $1,500 per acre, the opportunity of a lifetime