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 My name is Unal Kazak,
I am not an engineer, but on the other side of the walk. I studied monumental sculpture and design.
My interest to the metal workshop and model engineering is just a hobby, for I like engines and mechanics. I design small mechanical robots and for that I keep needing hard to come by or complicated machined parts. So, I quite often found myself ordering materials and begging from local metal shops to be custom-made. Of course they drag their feet to do it, even though I pay satisfactory for them. My parts from the projects were tiny and required complicated and uncommon machining. Often after coming home I would need to correct them by filing and re drilling etc.
Eventually I decided to produce them all myself, after throwing away much needed part was machined carelessly and ruined of course. I ordered my first mini lathe simply out of curiosity to see if I could make some of the easy parts myself. So, talked to my wife and occupied one of the rooms 0n the first floor to turn into a workshop. I already had some of the essential tools. But the new lathe was something else. (It was like bringing a full grown tiger to your back yard as a pet, for kids to play with). It had its own space, special tools, noise and the chip’ lings to go with it. “It” was no joking matter, but, very friendly. Soon enough we all get used to it. After messing up several cutters and plenty of work pieces, we now get along fine.
I still kept taking some parts to local metal shops to be milled. Than as you guessed, here comes the Mill, a band saw and a bench grinder to go by. Having these two machines side by side in 3X3m room and all the other tools, benches, vices, I had no excuse to go to the industrial parts of the town to waste anymore time and money. Now, I only go there to buy some raw materials for turning and milling.
I had been watching quite a while for model and steam engines but had no courage to start. I was also browsing some model engineering sites on the internet, but they were all advanced and I couldn’t bring myself even to ask them a question, than I saw this site… And I decided to write to John Somers. I am glad I did it. He was very helpful, inspiring and encouraging kindly pointing me in the right direction… and what came out of it? Well, here it is, my first engine;
Elmer’s #25 Wobbler. I still have to polish and perfect it. I admit it was a thrilling challenge and experience.
“Thanks for the support, John.”
Unal Kazak,
Mersin/TURKEY
Elmer’s #25 Wobbler
The adventure begins ! I was extremely focussed and careful. I used very sharp cutters and constantly watched RPM and feed speeds. I measured twice and measured once more before cutting. I tried to follow all the rules and played by the book. I even wore safety glasses over my close up glasses which in the past I often ignored.
Wear yours too. You know there is saying that “Wear your safety glasses! Even, if it saves one of your eyes, for one time.., it is worth it…”
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Found scrap pieces of a suitable size for this project. I decided for appearance and durability I would use stainless steel and brass.
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For the body frame and the base parts I found this piece of metal, it is too heavy to be Aluminum, but med-hard steel yet silvery shine, honestly don’t know what kind of alloy it is.
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I start out with the body frame alloy piece to square, parallel and face it.
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I used my favorite fly carbide inserted cutter to face and flat the surface.
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Metal dyed, lay out and marked all the outline and drilling locations before cutting to size.
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Precision locating by homemade with centering tool on the mill, where to drill, by locking X and Y before drilling operations.
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I start for locating and pivot holes with using small starter drill to make sure the drill bit won’t wonder around when I start drilling.
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Drilling 2.5mm for pivot hole.
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Enlarge the hole to 3mm. I could probably drill directly at 3mm because it is small enough, but didn’t want to take any chances. Here the hole must be square.
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The same sequences of procedure applied for locating hole two (crank shaft hole) Drilled 1.5mm for intake and output port holes.
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Finished the engine frame to final size.
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Turned the bearing from 10mm round brass stock and press fitted using mill’s vice, into the frame.
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Finished the body frame and bearing look like this. I accidently cut the foot part about 2mm short, so I will have to raise the foot up +2mm later.
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Cylinder block cut from brass bar and face milled, squared and paralleled.
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I try to make smooth facing as possible to leave less work for polishing later on.
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I don’t throw away my broken, worn out drilling tips and end mills, instead, I make marking, punching, and pointing tools from them, like most of us do. I just chuck it to hand powered drill and high speed run against running bench grinder, makes perfect pointed tip.
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Cylinder block piston bore location centered on the mills vice. Locked X and Y axis for secure pilot drilling. At the instructions, normally 4 jaw chuck on the lathe should be used for this operation. But, it takes too long for me to center and I have only flat independent 4 jaw plate. To get around it; I use the mill.
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Pivot hole starter on the cylinder block.
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Pivot hole drilled 2.3mm than tapped 3mm, 8mm deep. Using mill to tap to ensure squaring and the mill’ chuck turned slow and easy by hand.
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Turned 3mm for pivot pin from 6mm round stock brass. I am extra careful here because cutting tool will push and bend the pin away for I didn’t use tailstock center instead I used very sharp and tiny cutter while turning and take very fast spin but small passing. After threaded the pivot pin at the one end for 8mm long. Loctite and screwed to cylinder bloke pivot hole at the mills vice. When we bore for the piston, this application will seal and secure the pivot pin permanently to the cylinder, without needing to solder it. Placed the drilling jig over the pivot pin, locate the intake hole and drill 1.5mm
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After starter drill, started drilling from small diameter to large; M4, 6.5, 8.5, 9.5 and finally, with 10mm two flute end mill for piston bore. That provided the flat bottom and placed the reamer at the same time.
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To take a break, I turn simple 5mm dia.and 15mm long from brass round stock and drilled inside 3mm the steam intake pipe. Made groves at the tip of the pipe to provide secure fitting of aquarium tubing.
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Threaded 5mm using tailstock to make sure it is square (I don’t have die holders, yet to make them for now, I get by using tailstock for straightness.) Turning the chuck by hand.
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3.5mm threaded on 5mm dia.
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Start turning piston head from 12mm hex stock brass.
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Piston head drilled 2.3 and taped 3mm in advance for piston rod.
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Made some oil grooves and parted with parting tool.
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Piston rod turned from 6mm brass stock.
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The rod from solid 6mm dia. brass threaded at the end 5mm and placed the mill’s V grove and milled 1mm from each side and drilled for the crank pin.
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Piston and connecting rod look like this.
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Crank turned from 22mm dia. stainless steel to size at 17.5mm dia. at the lathe,
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The crank piece kept a bit over size to handle at ease, carried to mill’s vice and drilled for center and pin holes, using starter and pilot drilling procedure.
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After drilling and marking at the mill, take it back to lathe and brought to size. (one might get dizzy going back and forth..) but, this is why I avoid using 4 Jaw chuck if I can help it.
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After corrected size took it back to the mill and added shape to it with 7mm 2 flute end mill for balance.
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Then part off on the lathe.
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The crankshaft turned from 6mm stainless round stock to 4mm dia. and press fitted to the crank. 3mm pin cut from an old 3mm drill bit also fitted.
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Crank, fitted shaft and pin look like this.
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Brass flywheel faced and starter and center drilled for the crank shaft.
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Made an arbor and securely fastened the flywheel in order to face both sides.
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On the mill, marked, drilled 2.3 and tapped 3mm for set screw to secure the wheel to crank shaft.
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And the finished flywheel looks like this.
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I assembled the parts to make a quick check for any binding, friction or faults… so far, all is moving smooth.
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I chamfered the edges of the cylinder to give some extra shape for the looks and also help reducing the weight.
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And I also turned from a 10mm hex brass stock a small nut, drilled 2.3mm and taped by 3mm taper for the pivot pin and find a suited spring from a ballpoint pen. The cylinder and pivot pin looks like this.
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Here are all the parts completed. Need a lot of cleaning off the machining marks and the polishing yet.
……..and now, the completed wobbler
 Elmer's #25 Wobbler engine recently completed by Unal Kazak from Turkey. Congratulations to Unal for the excellent workmanship in completing Elmer’s #25 Wobbler.
Also a big thank you to Unal for taking the time to record each stage in the build project. I know from my own experience that when you become intensely involved in the build taking photographs can be an intrusion.
 Elmer's 'Wobbler' #25 The perfect choice for your first engine
The choice of your first engine build project is critical and should follow the ‘KISS’ principle.
Keep It Simple and Straightforward!
Get it right and you will get a huge buzz and a big smile on your face when your creation leaps into life!
* Go for a simple oscillator design.
* There are fewer moving parts.
* It will not require sophisticated tooling.
* It can be built in a matter of days.
* The forgiving design improves your chance of success.
Free Plans !
In my view you can not make a better choice than one of Elmer Verburg’s classic designs. His ‘Wobbler’ #25, for example is well worth a look at and the plans are free – available for you to download complete with build notes from
http://www.john-tom.com/html/ElmersEngines.html
This was the choice of Tim Evans of Northern Ireland – a professional photographer (which becomes apparent when you view the superb quality photographs of his build sequence which Tim has kindly agreed to share with us). Click on each thumbnail for a larger image.
Tim had the benefit of owning a milling machine but this is not strictly essential. Providing you have a lathe for all the round bits you can get by with hacksaw and files for the flat bits. Similarly for holding smaller parts in the lathe a collet system is useful for achieving a higher level of accuracy (reduced run out). This could result in improved running of the finished engine but Elmers #25 is a very forgiving design and tolerances are fairly accommodating – anyway over to Tim………..
Well after being advised to try a simple wobbler engine as my 1st project I’ve decided on Elmers #25. The fun part has been converting the imperial to metric measurements.
So I dug up a little slab of 6mm ali plate and hacked off a piece approx the size I needed. Then came the 1st issue to overcome, as the biggest milling cutter I have at present is 6mm I felt it was unwise to size the frame piece in one pass. So I took off my milling vice and decided to clamp the frame to the top of a 3-2-1 block that was squared up to the table, and use the side of my 4 flute mill to size.
Once sized up I then marked up for drilling,
After boring all the holes I tapped the intake M4, I meant to tap it M3 but messed up the drilling :doh: so I had to enlarge to M4 as I dont have a M3.5 tap.
So after drilling and tapping all the relevent holes the frame was done, or at least it was machined, I have to clean it up and polish it up a bit.
I then moved on to the cylinder. I had a piece of 19mm square brass bar. This presented a new challenge, I dont have a fly cutter or a milling cutter over 6mm. So how can I machine this 19mm square bar to 17mm x 15mm, and get a reasonable finish?
Up steps the 4 jaw chuck.
I remember reading somewhere about how to turn a cube using a lathe, and I just borrowed the idea, and what do you know, it worked!!
So I now have the cylinder blank sized and ready to bore, and that’s as far as I got.
However, in the process of sizing on the lathe I found out that getting a nice finish relies on smooth advancement of the cross-slide. ( yea, I know that you all know this, but it was new to me ) I found a bit of a cheats way of taking the monotony out of winding it back and forth, and getting a better finish. I just attached my cordless drill to the capscrew holding the handle on the cross-slide and just ran it on a low speed. Got a far better finish than I could’ve got otherwise. You just have to be careful to keep the drill in line as best as poss.
Here’s a pic of the completed (but desperately needing cleaning up) frame and the prepared cylinder blank.
I spent a total of 3 hours to mark out and bore just 1 hole The marking out went easy enough, and I even managed to center punch on the “x” :headbang: I even got it mounted in the 4 jaw and centered up within a gnats whisker.
The center drilling went well, and even the drilling with progressively larger drills until the bore was 3/8″ ( this time I had an imperial drill set, so no metric convertion needed ) It was at this point I realised that the 9.5mm and 10mm reamers I thought I had as a part of a set were not there, the set only went up to 8mm and all are hand reamers, not machine reamers, and so even if the set went up to the needed size they would be useless as the bore is blind and only just over 1″ deep.
So this is where the newbie-ness gets a little more obvious, instead of thinking that I could get a correctly sized and type (machine) reamer in a few days time, this numpty decided to spend 2.5 hrs trying to make one.
Sense has finally prevailed after making the bore look rather rougher than when I had just drilled it, and so I called it a day before I totally wrecked the cylinder blank.
So a total of 3hrs to bore one hole, and even that’s gonna need reaming out.
This is what it looks like,
You wouldn’t believe how much of a numpty I feel. When I read your post Bogs it hit me like a ton of bricks, “I have a boring bar set for my mill” :bang: (looks around for the hole in the ground to appear ) But I will file your C-o-C for future reference thankyou very much
Anyway, when I finally got over my numptyness this is what I got done today. I mounted the cylinder blank into the 4jaw, centered it and then took a couple of light skimming cuts and then about 4 repeated cuts to eliminate any springing of the boring bar.
I then remounted the cylinder the other way and bored out the pivot pin socket being careful not to break through into the piston bore.
Onto making the pivot pin. I didn’t have any small diameter brass bar and I didnt fancy wasting some 3/4″ square bar. I thought I’d try and be clever and use a little piece of 19mm x 3.5mm flat stock and turn it down. So I cut some off and chucked it in the 4 jaw.
Then to turn down the other end I wanted to chuck it in a ER32 collet to not leave markings on the pin, but I dont yet have a ER32 chuck for my lathe, but I do have a MT3 ER32 chuck for the mill, and the headstock on the lathe is also MT3. Not having a long enough drawbar I brought up the tailstock to ensure that I wasn’t chased around the workshop.
continued in part two
Once the pivot pin was turned down to the right size to be tapped M3, I then cut the M3 thread. You probably noticed that the tailstock is removed for this, I ran the lathe at the lowest speed ( I thread at the lowest speed so I dont run into the chuck ) and as I found out when trying to remove the ER32 chuck it was well stuck in there.
Once that was done, I removed the pin and then loctited it into the cylinder. (it was a pretty good press fit)
And that’s as far as I got today. Thanks to Bog’s for reminding me of what I actually had sitting in the corner of the workshop.
I managed to sneak a couple more hours in the workshop this afternoon. I started off by hacking off a little lump of brass for the piston and chucking in the 4jaw, turned down half to diameter.
I then chucked it the other way round in the ER32 collet but made the error of not tightening it enough and it came loose just as I was parting it off to length so I added to my collection of spare “smaller than I wanted” pieces and hacked off another lump of brass, chucked it and turned it down as before. This time I also drilled and tapped M3
I find this to be a good method of tapping on the lathe, to explain; The drill chuck is not jammed in the MT of the tailstock, it has some grip but is free to turn with light pressure. Also the tailstock is also free to move on the ways, and the tap in the chuck is also loose enough to turn if the tap jams in the work. I then run the lathe at a very low speed.
So that’s all I got done today, just 2 pistons made, 1 junked and one that fits ok. If I put a M3 screw in the piston and slide it into the cylinder and turn it upside down the piston gently slides down and stops at the entrance of the cylinder, with out the screw it just falls out. I dont know if it’s too loose, if I pull the piston out rapidly I get a satisfying “pop”.
Things I’ve learnt today;
I learnt that my ER32 chuck has a runout of 0.02mm,
Always start off with a piece of metal that is longer than you need as it makes life easier.
I also tried making a con-rod out of 303 stainless, it didnt go quite as planned but I learnt that it really helps to use sharp carbide tooling and that it doesn’t like my Hss threading tool.(prob was a bit dull, I must resharpen it) I’ll try again the next time with some brass as per the plans.
Also learnt to think a few steps ahead to see what I can do while workpiece is still chucked and true before taking the piece out and then spending 15mins truing it up with the trusty dial indicator.
And finally, always remember to check that whatever chucking device is used it is properly tightened up.
Today’s update.
I started out by sharpening my threading tool and spending 15-20 mins trying to single point 3mm 303 stainless for the con-rod. Deciding that beating my head against that particular spike was not fruitful :bang:, I moved on to machining a new con-rod out of brass. This was much easier.
Then I extended a bit more out of the chuck and turned that down.
Once turned to size it was over onto the mill, I mounted it into the spin indexer thingy, supported the free end with a 3-2-1 block and a little stepped thingy and drilled out the hole for the crank, 2.4mm if I recall correctly.
After a little cleaning up and filing the edges round I have a piston with con-rod
After that I had a little time so I made a start on the crankshaft assembly, specifically on the crank disc which I made out of some unidentified steel, turned some down to 17.5mm, hacksawed it off and remounted it in the ER32 chuck, faced it off and then drilled it 4mm.
Ok, managed to get a couple of hours in the workshop today. Started off by setting up and drilling the offset hole for the crank pin.
The more observant of you will have noticed that the Crank-disc is not properly seated on the 3-2-1 block and so did not drill square. I didnt notice that until I’d finished today and as I’ll explain in a bit I may have to re-bore the pin-hole square. Anyway, after that I found a use for the screwed-up piston, I turned it down to make the crankshaft bush shown below in the middle of the other hacked out bits.
I then chucked up a length of 6mm 303 stainless to turn down for the crankshaft, I turned down to 5mm for the main shaft and a short section 4mm to fit the crank-disc.
Then I did something similar for the Crank-pin, except I started with some 4mm stainless, turned it down to 2.4mm for the press fit into the crankdisc and 2.3mm for the easyfit into the conrod. I also pressed the crankshaft bush into the frame, after I cleaned up the frame,
then did a little assembly just for fun.
Once I did the assembly and tried to turn over the crank I found that it was sticking at TDC and BDC. After a little wondering I checked the squareness of the crank-pin ( it’s amazing how hard it is to use a 4″ engineers square on a part that’s only 17mm wide and the pin’s only 3.5mm high !!) I then realised that the crank-pin is not square and is what is binding up twice per revolution. I’ve not totally decided what to do about this. I could pull the pin out and re-bore the hole wider and square and then make a new pin to fit. Or to just try and bend the pin to square. I’m leaning towards just bending the pin back to square, and that’s what I did.
I managed to make a start on the flywheel, and got one side shaped, to a fashion, and today I bored and reamed the 5mm hole for the crankshaft, then remounted to machine the other side, centred it using the 5mm hole as a reference and then shaped the 2nd side. ( I was so excited about getting so close to completion I forgot to take any pics of these parts )
I then turned a some 6mm brass rod to a close fit for the flywheel, and threaded the end M5, and mounted the flywheel to it to clean up the rim and make sure (hopefully) that I dont have a wobbly flywheel.
After that I drilled and tapped the flywheel for the setscrew I then turned to the air-intake-to-aquarium-type-tubing-adaptor-thingy. I used the same 6mm brass rod and turned some down to 4mm and then threaded it M4 and then bored it through with a 2.2mm bit
Then after some jiggery-pokey with a parting tool,
It was over to the spin-indexer to make a nut-shaped bit.
continued in part three
At this point I did a quick mock-up of all the parts and positioned the crank for transferring the hole position from the exhaust of the frame to the cylinder. Then after removing the indexer from the mill and clamping down the vice, I drilled the cylinder with a 1.6mm bit.
I then found a spring that was about the right size and assembled all the bits together, and here’s the result.
( notice the immaculate chatter on the flywheel )
The other side
Imagine my joy, now to get it running. But how? I have a little air compressor, but no way to attach the length of 3mm (id) tubing to it :bang:
So I decided to build an adaptor. I just copied the connector off one of my air-nailer, and bored a 4mm hole up the centre.
I then made another air-intake-to-aquarium-type-tubing-adaptor-thingy as above, except I haven’t milled the nut-shaped-bit on it yet as I had to come in to make me grub, and that’s all I got done.
I started today with the air-hose adaptor that I started last post, I drilled the other end and tapped it M6, and then I milled a flat and then drilled and tapped M4 for the air-hose-barb-thingy.
Then back onto the lathe, I chucked a 6mm brass rod, and turned a 5mm to 3.5mm taper on the end. This is gonna be the inner tapered pin that will block or let a controlled amount of air through to the air outlet.
Then I threaded the rod M6, and then knurled the end
(notice the slight mess-up on the threading, I hadnt got enough of the rod sticking out and didnt match the thread up well enough during the 1st pass on the 2nd section :doh:)
But when put together it fits and works ok. There is a little leak of air from around the knurled/threaded area when the home-brew valve is open, but not so much that would bother me at the moment.
I then made up a round base out of some ali bar I had, drilled it and counterbored for the mounting screws, and also drilled and tapped a center hole M6. The center tapped hole is for mounting the Ali base onto a wider turned wooden base that I plan to make. (if folk are interested I’ll do a project log on that too)
Here’s the little wobbler on its little base.
And then, (drumroll please)
It runs
I finally got round to finishing off this project by turning a wooden base for it. Now this is more familliar territory for me, and while I did this on my woodworking lathe, the techniques are the same on an engineering lathe equipped with a toolrest. 1st of all I got a chunk of oak that happened to be around my dad’s workshop (that’s where my woodturning lathe is residing), and that chunk of oak just happened to be quartersawn ( nice looking grain ).
I then marked it out with lines on the diagonals. This was because I was going to mount it on the faceplate, but then I realised that I had my external jaws on my 4jaw self-centering so I just gripped it with that.
I then turned a dovetail recess on what will become the underneath of the base. ( this was to match the dovetail jaws that I then mounted on the 4jaw ) then I removed the oak from the external jaws and bandsawed it into a rough circle. (the only type of circle I can cut on a bandsaw )
Then I mounted the dovetail jaws onto the 4jaw, and mounted the oak base onto them. Then I turned a recess to fit the ali base of my elmers#25.
I then turned a concave section, 2 flat bits and 2 tiny grooves.
Then I sanded it 120,220,230 and then 420grit, burnished it with 0000 wire wool (sourced locally from steel sheep :lol: ) Then I finished it with quick-drying friction polish, then I polished it up with some canuba ( I think that’s how it’s spelt :scratch: ) wax.
These are the tools I used,
I find woodturning a very tactile experience, when I started to turn the base I didnt fully know what shape I was going to make, the wood sometimes just lends itself to a certain shape. The shape just flowed on this one.
The key to getting a good finish off the tool is to let the bevel of the tool rub against the wood as the tip cuts, this gives a clean cut and also burnishes the wood, this is especially true when turning woods that are not close-grained (such as Oak, Pine, Balsa … )
Anyway, I spent some time today doing some final photos of this project, I’ll post up a bit about how I did it in my post about photography.
But here are 2 pics
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