Tuesday, December 24, 2019

Puzzle Board

My wife wanted a board for her classroom to put puzzles together that could be moved into a back room.  She wanted felt on it.  We started by picking up a decorative "trim" (it was a moulding from Home Depot) and a large plywood sheet.  We cut the trim down to size, and then glued them into place.  I'll tell you, I found a new use for tie down straps - they make good clamps for the gluing process.

I did have to glue some added support on the underside to keep the edges from being broken by classroom kids.

Once glued, I coped the corners, sanded it down, and learned that it was no longer going to be painted.  She wanted it stained.... dark.  I used a dark walnut stain.  I did the bottom side of the board, but left the front side so that it can still have the felt added.  Surprisingly, the plywood doesn't look so bad.

I still need to tack the felt down.

Sunday, November 24, 2019

Wrong Intake, and Making Custom Gaskets with a Silhouette

While trying to get the corvette started a few weeks ago, I found an oil gusher coming from an exposed oil hole on top of the engine block.  It's not the original engine, but it is the original intake manifold.  Please note, it IS a first generation small block.  My mistake was to assume that all first generation small blocks are identical or compatible.  They are not.  So, it was time to do some decoding.  I grabbed pictures of the ID numbers on the block and on the intake, just to make sure I had the details.

Here's the firing order, just to post it for posterities' sake.

The block offers a little more detail.

So, I have a 14057053 intake manifold (lots of virtual links to 1980-1985 Chevrolet 305/350 engines), and the engine block has V0228TKS engine code that matches a VIN of T4U511082 .  The block ID of V0228TKS looks like it was made in Flint, Michigan.  The 0228 are a date stamp, meaning February 28.  The rest of the letters (TKS) on the end indicate it was a 1974, 1978, or a 1980 small block, and destined for use in a van or truck (on really old engines, the three letter code starting with a "C" for cars and "T" for trucks).  Prior to 1970, the suffix codes were only two digits.  So, we know we are at least 1970 and later.

The VIN part helps us isolate it between the 1974, 1978, and 1980 model years.  The start of it indicates the manufacture target even more.  Starting with a number 1 would be for a Chevrolet, 2 would be for a Pontiac, C for a Chevrolet truck, and a T for a GMC truck.  The second digit of the engine VIN represents the last digit for the year code (number in the 1970's, letter in the 1980's).  The next digit (a letter) represents where the block was manufactured.  I have a "U".  The rest of that VIN code should match to the last digits of the vehicle the engine went into, so I don't care about that.

So, this was a first generation small block engine that was made February 28, 1974 in Flint, Michigan for a GMC 350 truck that was assembled in Hamtramck, Michigan.

I ordered a carburetor adapter for a holley 4160, I know to order one for a 1974 GMC C10 350 cui.  It was for a rochester system.  However, it did not fit.  At all.  It turns out the intake was for a spread bore (sometimes I don't know why my brain doesn't work).  So right here, I went off on a tangent.  Scroll down for the results if you don't care to know how to create a custom gasket for something.  Search for "end of the tangent" to get past all of this gasket making stuff.

Anyway, I decided to cut a template to take with me to the parts store and see if anything would fit.

Time to break out the Silhouette - mans best friend for custom gasket making.  Here's what we need to replicate into both a pattern for the adapter :

Before cutting, you do have to design it. Grab a blank piece of paper and a crayon (or a colored pencil, basically anything using wax or lead, but crayons are seriously the best).  Carry those to the flat surface you want to replicate (you know, the intake manifold's carburetor surface), and place it on there.  While holding the paper still (so it doesn't move during this part of the process, or it won't match), carefully rub the crayon over the surfaces.  The corners will have a darker edge where the crayon wants to roll over to the paper where there is no surface below the paper.  This is precisely what you want.

Once you have the paper finished and can see the entire surface (you really want the edges highlighted), you can now transfer that paper to a scanner.  If you don't have one, libraries or friends with scanners can come in handy.  You do need to scan it for this process.  Granted, you could simply cut it out and use it as a pattern on your gasket material, but you don't get to do some seriously manly stuff like using a craft cutter, I mean, using a CNC cutter in making perfect gaskets.  So, load the scanned image into your editor (Photoshop works, but I like open source software and always use Gimp), and adjust the levels (sort of like a brightness/contrast, but better control over where the levels sit for it) :

Awesome!  Now we have a scanned image that we can see the edges with!  Save it out, and open another open source package, Inkscape.  If you've never used Inkscape before, you might need your wife to show you.  Granted, you can probably use Silhouette Studio upgrade for this, but old habits die hard and I have the basic studio, so I can't.  The intent here is to convert those visible edges into bezier curves.  Essentially, you are tracing a bitmap into shape :

Now, save your SVG, even though we don't really need the SVG.  Once saved, export it into a DXF (plotter/cutter).  This format can now be imported into Silhouette.  Open Silhouette Studio, and import it into your library.

Once in, you can insert the object into a new project.  I would suggest immediately selecting everything, clicking on object, and grouping them together so it is less likely to move one curve out of place.  Make absolutely sure that there are no cut lines across the resulting gasket before proceeding!  I'd get another blank piece of paper and load it into the silhouette, and send it to the printer at this time.

Grab that newly-cut piece of paper, carefully peel it off of the cutting board, and take it to your part to ensure it has the right fit.

The odds are not in your favor of having it fit perfectly the first time.  This is why we do a test piece, first.  Determine the adjustments, make them in Silhouette, and try again.  Keep doing this until you have the right fit.

Now, load your template material, adjust the Silhouette's depth of cut, and cut out your final template.    If you are making not just a template but a gasket, that's just fine, too.  Congratulations, you just made a custom, professional gasket for your engine!  Anyway, that's the end of the tangent (this is where that search above would bring you).  So, back to my case - I'd successfully located an adapter (though I'd rather try the Edlebrock spread bore to square bore adapter kit as it doesn't nullify the intake's separation of primary-vs-secondary chambering.

So here we go.  My intake used 3/8-24 bolts.  This Mr. Gasket (#1932) adapter was built for 5/16 bolts.  This is definitely not going to work.  But, I had a drill press, a letter 'U' drill bit, a 3/8 drill bit, and a 9/16" end mill (square, this is important).  I grabbed the adapter and ran over to the drill press.  Make sure the drill bits will extend into the drill press center so you don't drill holes in your table, get the table to the lowest you can do for your drill bit to get all the way through the adapter.  Lock the table into place.  I am using a 3/8-24 socket head bolt (so I can use an allen to tie the adapter to the intake.  So, what I've got to work with :

I first used the U drill bit to fit through the hole (drill press not running) and line the adapter up with the drill press spindle while clamping the adapter to the table.  Then you can change drill bits to increase the size of that exact hole to 3/8".

You'll find after a test fit that the bolts now fit through the hole (see above), but do not seat into it (the heat hole is too small).  This is why I used a 9?16" end mill - the socket head is just shy of 9/16" in diameter.  So, remove the drill bit (do not unclamp the adapter to move to the next hole because you'll lose the reference of the hole to the spindle), and put in the 9/16 end mill into the chuck.  Don't worry about it not clamping hard enough on the end mill, the adapter should be aluminum, and we're not putting side loads on it (we're only trying to drill a flat-bottomed, 9'16" hole for the socket head).

With that in place, slowly peck away at that hex socket until we reach the bottom of it (do not proceed below that seat that originally existed).

When done, you can test fit the bolt into the adapter :

You will note that the socket head sits slightly proud of the surface.  This will have to be remedied to be used.  I installed the 3/8" collet into the lathe and faced the bolt until I had the right height.  You can easily use an angle grinder to eat away at it until it is low enough.

Now, it's time to install the adapter.  It should be fairly easy.  Just drop the gasket into place, set the adapter on (in the right direction, of course), and install the bolts (don't forget to have the other bolts in place before you install the adapter).

With the carburetor bolted down :

Next up is to run the fuel lines.  In the above picture, those lines are going to be replaced. They are terrible.  I have to bend them to match the angle coming off of the carburetor so I can clear the block off plate and the A/C fitting toward the front.  Here, let me circle those for you :

So, I need to custom run a fuel line.  I do not want to be replacing rubber every few years, so I have to go with a hard line.  Because the newer, non steel lines would require supports, I have to do either straight steel or stainless steel.  We'll see where I get.

Tuesday, November 12, 2019

Made a Wood Lathe Insert Tool

I love my old Dunlap wood lathe (534-0601).  It is a blast to do wood work, really.  This was made in a few different variants, such as a Power King, a.k.a. Atlas (who actually made it for Sears).  Under the Sears moniker, it came known as "Craftsman", "Dunlap", and also "Companion".  It is similar to the Harbor Freights of today in that one maker is manufacturing for many different brands with a few minor modifications.

I had already built a carbide wood turning handle (round), and wanted some additional ones.  I used the Hazard Fart (stupid spell check) to mill out a seat, and then drilled and tapped it for an 8-32 hole and dropped in the diamond insert.

While I was there doing metal work, I was welding a new stand for the Dunlap wood lathe, and dropped a square tubing from 3 feet onto my finger.  Not pleasant.  It definitely hurt.

Meh.  I chiseled out a groove to match the rod and glued it together, turned it on the lathe, and threw on a copper pipe cap as the ferrule (I did drill it out and file it square to match the square rod).  After coating it a few times in boiled linseed oil, I have a functional (and complete) tool.

Now to find a new project to use it on.

Wednesday, October 23, 2019

New Shop Tool - Old, Obscure Dividing Head

I've needed to create a gear to finish the hand lever collet closer attachment.  This meant I needed a good dividing head (well, I had the small rotary table, and could have done just fine with that one, because a 40 tooth gear is perfectly divisible on a rotary).  I ordered an old dividing head off of eBay. It's time to get it identified.

It appears to be labelled as a "Republic Tools", and the "1161" prefix stamped into the spindle was also stamped into the bottom of the casting (matching numbers... that's a good thing).  It rotates very smoothly, so it's been well cared for.

Typically, a dividing head is a 40:1 ratio, meaning you turn the handle 40 times and the spindle turns once.  This one looks different.  It felt like a 48:1 with the brief check I ran.  I will have to verify this, but it felt less like a 40:1.

The spindle through hole is about 1" (0.923" in the back, probably just an awkward angle and not accurate in any form of the word, and about 1.050" in the front).  There is no real taper on the bore of the spindle, so it's not 3C compatible.  It is definitely not 5C, or a morse taper.   That is going to force me to use the threads for any indexing purposes.

The spindle thread is 1 3/4-8 TPI, so it's an older thread that I might have to build an adapter or a backplate.  I'd like an adapter do I could potentially move from the lathe to this without removing the workpiece from the chuck itself, then things are more likely to be concentric if I need to change machinery between turns.

My brain went immediately to trying the infamous 127 tooth gear so I could potentially cut metric threads on the lathe, and that lead me to check the diameter of the hole plates :

At 4.875" on the outside diameter, if I ran a hole pattern around a 4.5" diameter circle (14.137155" of travel along that diameter) and divided that 127 times, we'd have 0.11131618" between holes along that path.  Seeing as that hole pattern would not have enough material between holes (let's call that "meat"), it could not be a 127 straight-line sequence.  I would have to offset the holes to get a good pattern into at least two rows, but considering 127 is a prime number, it should be three rows (or you end up with two holes on the same path right at the end).  Is that doable?  Absolutely.  I might just have a shop put the holes in the plate for me, though the accuracy isn't as critical for them because I'd be using that to bootstrap another 127 hole plate.  If another shop did it for me via CNC, I'd not need to bootstrap it - it would be accurate enough.  If I do it myself, I would use the index plate to make a second index plate (causing it to be much better in accuracy on the second one at 48 times, if the ratio is 48), and then I'd use the second index plate to create a third index plate.  This would improve the accuracy 48*48, by 2304 times.

Anyway, I need to adapt a chuck to it.  The chuck is a K72-80 (80mm) independent 4 jaw chuck.  I cut a backplate out of some cast iron and bored it to 1.595".

I used a threading tool to cut some basic threads (not big enough), and then used a boring bar at as much of an angle as I could manage to hog out as much thread material as I could.  I grabbed my 1 3/4-8 TPI tap, and man-handled that thing through the bore to get my thread.  This caused the bore and the face to be perfectly aligned (centers even).

While there, I faced it down to match the chuck.  I had to check that the thread was correct, so I spun the dividing head into the thread so I didn't have to re-clock the thread when I removed it..

Successful in the test fit, next up was to identify the bolt hole information so I can drill the holes and mill out relief for the socket head bolts to hold both together.

At 2.25" from bolt to bolt, on a three hole pattern, I could then start some calculations to convert that into usable information.  Frankly, I need the bolt radius.  I started out doing some serious math to determine the diameter/radius.  I spent a half hour doing math using trigonometry before I thought, "Why?"

I ran and grabbed the machinists handbook, looked up the circular segmentation chart, and on a 1" diameter piece of stock, the 3-hole pattern had segments of 0.866025".  Here's where we get tricky.  Because the table listed a diameter of 1, it should be a simple algebraic format :

Segment_Distance=Diameter * Segment_Value

Quick flip of terms to reverse what we need (we need the diameter, not the segment length), followed by isolation of terms :


Add our values :

The 2.598, is the diameter of the bolt circle.  The radius (distance from the center) is what I need - to know how far to move it once I have it centered.  Dividing by 2 gives a radius of 1.299".  I grabbed the calipers and set them to 1.299" and lined it up with the center.... viola! That's what I need.

I jigged up the scariest setup of my life on a mill.  It was a matter of using an angle plate (on 1-2-3 blocks to get it tall enough), and a lot of sketchy clamps.  I even had to clamp the back plate to the indexing head (only once it was in position).

I could mill the bolt head pockets, but I could not drill the bolt holes (the mini mill doesn't have quite the work space to use a drill chick and an indexing head on it's side.  Once I had the pockets, I could use a collet to hold a center drill to get those started, and then finished the through holes on the drill press.

Now, it's still too tight to install.  The back plate went into the freezer for a few hours, and the last 20 minutes of the freezer, the chuck went into the oven.  They all came out at the same time.  The different temperatures on the material gave enough expansion/contraction distance that it could be easily bolted together.

With that mated up, I could reverse chuck it into the lathe and face off the back, then add the clearance for the thread.  I first parted it off :

Then I faced it and clearanced the thread :

And finally installed it :

I'd call that a success.  I can now cut the gears (if the table is large enough to hold the dividing head, gear, and tailstock.  I did cut my first gear, but the setup time was extraordinary.  So, I had to change the 4 jaw independent chuck for a three jaw self-centering.  The only one I could find was a 4", and I didn't have a chunk of 4" cast iron for a back plate.  You don't want to try to tap the threads in good steel for a 1 3/4-8 TPI thread.  Trust me, the part just twisted in the jaws.  The only 1 3/4-8 TPI pre-formed back plate is actually much larger - I could only find it for a 6" chuck, so I ordered the 6" back plate.  Here's where things get tricky.

When you attach a chuck to a lathe, you have to machine the backplate on the lathe to maintain concentricity.  It is an absolute must.  In this case, it's going on a dividing head, so if you machine it on a lathe, you will end up with the chuck center line offset from the dividing head center line.  Simply put, you have to machine the backplate on the device it is to be used for.  Have you ever machined a backplate for a dividing head?  No?  Here's what to do.

Taking a 6.25" back plate to be used on a 4" chuck, you need to hog off a lot of material.  Also, I needed about 3/4" of depth, and this back plate is 1.25" deep.  I used the lathe to break down as much of the outside surface as I could.  You must leave it oversized, because you will still machine the plate on the device it will be used on.  So, after the lathe, I'd removed a bit of material.

After removing that, I could put the backplate on the dividing head backwards.  This would allow me to face off the rear surface that mates up against the dividing head.

Once that is surface is machined, I pulled the backplate off and turned it around.  I could then machine the outside edge down to match the chuck.  In this case, the chuck was 3.948", and at this point the back plate was 4.250" in diameter.  I machined off 0.030" using the mill.  You must be careful here.  As the end mill rotates, the direction where it meets the backplate must tighten the backplate instead of loosening.  The speed of the dividing head is minimal, so we don't need to worry much about having it round.  It's nice to do, though, for a finish.

With the outside edge, you can now machine the mating surface for the chuck.  This should be done very slowly - it is the same principle as doing it on a lathe, but the part isn't rotating, and you are taking it off with an end mill.  Remember, when you take off 0.125", it removes twice that because it takes the 0.125" off the other side, so it's really taking 0.250".  Take your time.

After the boss for the chuck has been cut, you can surface the boss so it is deep enough.  At this time, you can rotate the dividing head and drill your holes for mounting the chuck.  I flipped the back plate again, so that the indexing-side surface was on the outside.  This allowed me to bevel the rear flange for clearance on the screw caps.

With that complete, it is now time to pull the plate off and install the chuck.  That completes the installation of a new chuck to a dividing head.