Skipjack by michael mott - 1/8th scale - SMALL - 19 foot open launch

[michael mott]

Thanks Denis.

 

Not a great deal of progress over the Christmas, too much food intake and family visiting all very enjoyable of course.

 

I spent a little time today mostly building a special collet for the 1/8th shaft mills and drills which I would normally use in a drill chuck, but using a drill chuck for milling is to court disaster. I used some free machining 3/8 mild steel for the collet, this tool will only be used for light work.

First I turned it down to 1/4 and threaded the locking end 1/4 x20 to fit into the 1/4 collet in the Clarkson collet holder for the mill then it was drilled with a #31 drill and reamed 1/8th for the 1/8 diameter shank drills and mills.

 

the end was threaded 5/16 x 24 and the end 1/2 inch was cross slotted with a .014 slitting saw and a 41 degree taper was turned to match the 82 degree 1/4 diameter countersink that I have. A locking nut was machined out of a scrap of 1/2 inch diameter mild steel and a couple of flats filed onto it for a wrench

 

All this was done so that I could actually see what I am doing because with the small diameter end mills the Clarkson collet holder is too big a diameter and really restricts the view when using the small diameter mills.

 

 

 

Tomorrow I will do some work on the inside of the piston.

 

Michael

 

 

 

 

[Bedford]

That's the mark of a true craftsman, spending hours making the tool holder to make the part properly.

 

I wonder if I will have that kind of patience when I get more into machining things.

[captainbob]

Great idea.  Now you can see what you are doing.  Well done.

 

Bob

[michael mott]

Steve and Bob thanks for your nice comments, and to all who have added likes.

 

I ended up making a new holder and some new pistons (it would be nice to only have to make something once for a change)

The new collet really does help a great deal being able to see clearly what I am doing. the new holder also is a bit stronger, the firdt pic show drilling the 1/16th hole for the wrist pin.

 

 

the finished pistons with the rectangular cavity and the wrist pins temporarily in place.

 

 

I have turned down the blanks for the con rods,

 

 

 

The next operation on the con rods will be to machine the large diameters into flats, then bore the hole for the crank , and drill and tap the crank end before splitting it with the slitting saw. then the big end will be re assembled and rebored for the big end bearings

 

 

piston and con rod.pdf

 

Michael

[jud]

Aluminum pistons is the norm for most real life engines. It's the "O" ring that surprized me, was expecting some Iron Compression rings and an oil seal. I remember the rubber seals for bag type guns I worked on, wondered why they didn't burn out. Seems that if the seal is good, rubber works fine, it's when a leak develops trouble begins with hot gas rushing through the leak destroying the rubber seal, expect the "O" ring works the same.

jud

[Jaekon Lee]

It's really another world of modeling.@@ Great job, Michael.

[Remcohe]

Michael, your metal work is exquisite and a joy to watch.

 

Do you use some sort of sensitive drilling attachment when you use the PCB drills? Mine always break whenever I use them in the mill or drill press and whenever possible I revert to drill small holes by hand (a tedious task.....)

 

Remco

[Omega1234]

It's really another world of modeling.@@ Great job, Michael.

Not only is it "another world of modelling", but it's beyond comprehension just how difficult it is to do what Michael's doing. Truly a job for the seriously skilled!

[michael mott]

 

It's the "O" ring that surprized me, was expecting some Iron Compression rings and an oil seal

Jud this is what surprised me the most as well, I am following the same practice as many of the model engines that have been built by the model engine builders and the most important thing is to make sure that the cylinder liner is well polished when using the O rings which is opposite to using cast iron rings. There are a number of tutorials for making cast iron rings down to 3/8th diameter but it takes a bit of practice and some really good cast iron bar stock to be able to make them successfully.  

 

JKLee and Omega

Yes it is a different area of modelwork but basically one only needs to focus on the task at hand and break it down into incremental chunks small chunks I admit. The way I see it is that each time we change materials or scales we encounter new challenges and have to consider using different tools for some tasks.

 

 

Do you use some sort of sensitive drilling attachment when you use the PCB drills? Mine always break whenever I use them in the mill or drill press.......I revert to drill small holes by hand (a tedious task.....)

Remco the short answer is no, that said I think that the basic issue with drilling small holes is one of sequences.

 

1)  When drilling into wood with very small drills 1/32 and down to the small #'s 60-80 the wood is not a consistent homogenous material, it is organic and full of subtly different hardness's and textures and this is I believe the main reason for breaking the bits when using a drill press or milling machine, the other issue is the speed of rotation of the bit, the smaller the bit the higher the speed the machine needs to run, this is counter intuitive to the way we use them by hand in pin vices which is technically a snails pace by comparison. I think the difference is that when using a hand held pin vise we use much less pressure and can "feel" the drill cutting, remember our fingertips are one of the most sensitive parts of our bodies with the possibly the most nerve endings. 

 

2) When drilling metal the key is to ensure that the start is exactly centered, and I mean exactly, this can only be accomplished by using a centre drill to spot the centre first my centre drill for the small drills cost me $27 for a tiny 1/8 shank centre drill this means the for every hole I have to do a number of things first decide on where the hole is going to be, this entails laying out the position on the material and fixing the material solidly to the drill press or mill, I tend to use the numbers and not a centre punched divot, by that I mean indexing from two or more sides depending on the shape, the centre drill takes the place of the punched divot.

 

3) The way I index is to use an  edge finder or centre finder to set the datum on at least two edges then I can simply set the dials on the table to 0 and them index them to the two coordinates x and y that is the centre of the hole, I do this regardless of the size of the piece I am drilling, it is a habit. The quill of the mill also has a dial so that I can set the tip of the drill to 0 at the surface that way I know how deep my hole will be if I am not going all the way through. if I am going all the way through I sometime use some wast material as a support so that the drill does not catch and snag on exit one of the biggest causes of broken drills in the smaller sizes, the other is the drill bending because the start was off centre from the centre axis of the rotation of the drill as it gets deeper the bending forces increase often snapping the drill.

 

4) The next important thing regarding wood or metal is ensuring that the drill flutes do not get clogged with the material what you are removing out of the hole, it has to go somewhere so raising the drill out of the hole frequently allows it to escape (this is usually centrifugal force that throws it off the drill) sometime the material is "gummy" some brass and some aluminum can be this way and so a lubricant (Varsol or Paraffin works well) is needed to keep the bit slippery, a cutting oil for steel. Obviously one doesn't need the lubricant on wood but it can clog the bit even more quickly than metal, so small "pecks" (frequent raising of the drill to clear the wood off the drill) a small fine stiff brush can be very helpful to clear this debris out of the flutes.

 

The last thing to remember is the depth to diameter ration of the hole deep holes are more difficult to drill for all the above reasons

Finally use the best quality drills you can afford and I always use a centre drill to spot the hole, this means that if I am drilling a number of holes I can drill all the centre spots first (following all the numbers on the index map drawing) then go back and follow all the numbers again with the drill this is the fastest way when I an drilling multiple holes to the same depth. Or I can change the drill from the centre drill to the hole size drill with each cut, it depends on what I am drilling and for what purpose I choose which way to go.

 

I hope this answers your question.

 

All of what I just said applies to using a drill press mainly, and also ensuring that the work is rigid (clamped in some way is also very important) when working freehand or using a hand held drilling devise drill or Dremel type tool similar conditions apply but they are not quite the same, and I take my hat off to all the steady hands out there, drilling treenail holes. I cringe when I read of using a # 70+ drill bit by hand.

 

 

 

but it's beyond comprehension just how difficult it is to do what Michael's doing

Omega actually this really applies to your Ingomar yacht model 

 

 

Michael

[Mirabell61]

beautiful machining work Michael,

 

Nils

[Twister]

(it would be nice to only have to make something once for a change)

 

Ah, but Michael, if a job's worth doing it's surely worth doing twice!! (Or an opposing view is that real idleness is doing it right first time... )

 

Having read your 'primer for drilling' I can concur whole heartedly with every piece of advice you offer - I've recently broken several 2mm bits trying to drill 35mm blind holes into aluminium & the only addition I'd make is that WD40 is also a pretty good lubricant. Now, if I can just work out how to remove the offending 'bits' of drill I won't have to remake the components...

 

As usual, absolutely amazing work / machining - even I'm beginning to get excited as the first firing up approaches!

 

 

Regards,

 

Row

[SJSoane]

 

Hi Michael,

 

Great tutorial on drilling small holes. I searched around for better drill bits last year, and thought I had made a great discovery of carbide drills with common shank sizes to fit my Foredom collet. But they all broke on the very first use. Back to the steel wire bits. When you say, buy the best you can afford, what brand are you using?

 

Best wishes,

 

Mark

[mtaylor]

That was a great tutorial, Michael.  I've printed it out and will paste it next to the mill and drill press.

[michael mott]

Thanks Nils and Row for your kind remarks, and to all who added likes.

 

Mark these are the drill bits I have purchased they are good quality general purpose from Acklands Granger The 1/8th shank bits came as a box of mixed sizes,  I got them from Lee Valley and that they got them from Drill bit city but I am only guessing on that one My centre drills are like this one ,in these sizes 0, 1, 2, 3.

 

Mostly I sharpen my drill bits as they get dull.  the ones I use the most are # 50-59 #'s 20, 43, 33, 36, 12, 8, 11, 29, 25,

and most of the fractional from 1/16 to 1/2 in the 1/64th inch increments I have a few metric drills specific to metric taps.

 

The smaller bits I sharpen with a small slip-stone holding both the drill and slip-stone in my hands for the bigger ones I use the big diamond wheel that I got from an optician as a discard when they purchased new equipment.

 

With the bits that I use a lot for brass and plex I use the slip-stone to put a flat on the cutting edge so that it does not grab but scrapes

 

Michael

[Remcohe]

Michael,

 

Thank you very much for your elaborate answer, this is very helpful. I now understand I need to add a few very important steps in my drilling procedure. One being to start using a good center drill  to mark the drill points.

 

Remco

[EdT]

Micheal,

 

Thanks for the tutorial on drilling.  I particularly appreciate the comments on indexing to locate holes.  I am doing a lot of small hole drilling in wood right now on Young America's planking.  Tight holes to hold the planks with pins when glued are #74 and holes for the treenails #73.  There are literally thousands of these on the model.  I always - always - center mark the wood with a sharp scriber and use a hand-held, pencil sized (Wecheer) rotary tool with either steel or carbide bits in a zero opening (Dremel) collet.  As I write this I am fiercely knocking on wood but I have not broken either of the two bits I am using in several months.  The usual cause of breakage for me is dropping the tool or whacking something with it.  I believe the keys are those you mentioned - center-marking, high speed, keeping bits clear - also, a very light touch with the tool helps.

 

I too, will be keeping a copy of your note.  Thanks.

 

Ed 

[captainbob]

I've recently broken several 2mm bits trying to drill 35mm blind holes into aluminium & the only addition I'd make is that WD40 is also a pretty good lubricant. Now, if I can just work out how to remove the offending 'bits' of drill I won't have to remake the components...

 

Regards,

 

Row

 

Wow, 2mm diameter by 35mm deep !  The machinists where I worked would not drill to a depth more that 10 times the diameter.

 

Bob

[pete48]

Beautiful work as always Michael , its nice to get caught back up on the build 

 

Best Regards,

Pete

[michael mott]

Thank you all for you kind comments regarding the notes on the way I go about drilling holes. and thanks for all the folk who liked it.

 

Pressing on with the con-rods the first order of business was to make a brass split holder for some of the following operations this was made from 2 pieces of 1/4 x 3/4 inch bar stock before I drilled and reamed the 1/8th hole through the joint I added two small slivers of .0015 shim stock to spread the bars so that when the con rod which  is 1/8th is placed between them the allen head cap screws will have that .0015 missing so that the bars squeeze the shaft of the con rod holding it firmly.

 

The first three picture show the stage 2 of shaping the rods the round ends have now been reduced to the correct width.

 

 

 

 

 

The next operation was to drill the holes for the split big end these are clearance for 0x80 bolts

 

 

After the holes were drilled the assembly was taken back to the lathe for the slitting saw to cut the big end into the two parts. they are temporarily held together for drilling out to .156" for the bushing. here they have been drilled and the hole for the wrist pin followed by indexing 1.004" (I'm not sure how it got to be 1.004" I'm just following the drawings)

 

 

The area marked in blue is to remind me that I will need to shape the keeper later and remove that areas marked with some files using a hard button to ensure that the curvature is maintained. I also need to turn up some steel bolts for the big end, and make the split bush, I will do this by soft soldering a couple of bars together then turn the bushing in the lathe then unsolder them ready to fit the rods.

 

 

removed from the jig so that I can get the second one to the same stage.

 

I'm tired time for a nap.

 

Michael

 

 

 

[cog]

Michael,

 

Again some marvelous work.

 

I have the impression you make as much utilities to make or improve/adjust parts as you make parts themselves ...

[captainbob]

Fantastic make the tool to make the part.

 

Bob

[michael mott]

Carl and Bob, thanks, Sometimes it seems that the jigs and fixtures take longer to do than the parts themselves.

 

Michael

[Bedford]

I like the way you will make the bushes, very simple and effective. Still in the front row!!

[michael mott]

I finished prepping the other rod this evening Also forgot to post the pic of how the big end was split. I used the slitting saw in the lathe.

 

 

I also turned up a pin out of steel to slip the wrist pin hole onto so that i could use the lathe as a shaper.

I used a round nosed tool bit sideways and moved the carriage back and forth as the top end was rotated incrementally by hand to shape the top round.

The first one is fixed to the piston I forgot to take pics of the shaping I will set that up for the second one tomorrow.

 

 

 

 

Michael

 

 

[Jim Lad]

B***** brilliant work, Michael!

 

John

[Twister]

B***** brilliant work, Michael!

 

John

Couldn't have put it better myself!!

 

 

Regards,

 

Row

[Twister]

Wow, 2mm diameter by 35mm deep !  The machinists where I worked would not drill to a depth more that 10 times the diameter

I appreciate your input Bob, just wish I'd known that before I started! At least the components I'm (trying to) work on are practice pieces in aluminium before the expensive brass comes out...

 

Regards,

 

Row

[michael mott]

Row, I am curious about the holes, again use a pecking process to drill the hole very small cuts and continually pull the bit out all the way to clear.

John thanks, and again for all the likes

Michael

[pete48]

Amazing work Michael, HAPPY NEW YEAR

 

Best Regards,

Pete

[druxey]

Beautifully executed Michael. Silly question, though: I always thought it was called a wrest pin, rather than wrist pin. Or is it the old tomayto/tomahto thing?

Either way, a happy and healthy New Year to you.