Sunday, December 7, 2014

Tongue Twister



Transmission tunnel triangulation tacked.

Garage Essentials


I picked up some garage essentials this weekend...Maybe this will finally solve the Sharpie-Cockroach Paradox.

Sunday, November 23, 2014

Blue Painters Tape

I'm not sure what it is about painting supplies, but they're just so damn useful for stuff other than painting.  I had previously written about using the stirring sticks for setting the angle on my band saw.  Now I'm using painters tape to lay out and cut my tubes to the right...err...correct angles and lengths.

The basis of this technique is something that I picked up from a friend for making compound angle cuts.  However, I decided to use it to see if it might also be able to simplify cutting some types of 2D tubes as well.  A diagonal tube between parallel planes in a rectangular opening is relatively easy to math it out.  But it adds another layer of complexity when the opening is not rectangular, nor symmetric for that matter, and the tube is not between parallel planes.  Thus I figured this would a perfect time to practice an alternative technique.

First I spent some time figuring out exactly where I want the tubes to go.  These tubes also happen to be going beneath the transmission. So I had to make sure to avoid the lowest parts of the transmission, try to leave at least some emergency access to the drain and fill plugs, and adhere to my personal guidelines of avoiding overlapping weld joints and angles tighter than 45 degrees.  The latter of which I forgot about last weekend until after the tubes were cut, sending me back to the drawing board...Literally.  No fancy CAD programs here.  Just good old fashioned graph paper, a pencil, and a ruler.



The process then starts laying painters tape across the span where the tube will go.  Measure out the desired corner points based on the design, marking them with a Sharpie.  After that, use a large enough straight edged device and play connect the dots.


Since the Sharpie can be seen through the tape, I find it easiest to lay the tape sticky side up on the table and align the tube on top of it.  Then flip it over to clearly see where the cuts will go.


Now my band saw only angles in one direction.  To cut angles the other direction, you simply flip the part over.  With both cuts going opposite directions, only one of them can be cut with the tape side up.  Align the cut line on the tape with the cutting blade, lock it in place, and let it rip.


With the tape having been cut as well, it now becomes the transfer pattern.  To make it stick to the other side of the tube, place a couple strips of tape sticky side up on the table, lay the transfer pattern tape sticky side down on top of them, and align the tube on top of that matching up the previously cut ends.  Now wrap the sticky side up tape strips around the tube to hold the transfer pattern in place.  Roll the tube over to see where the cut needs to go, and using a center punch or scribe, mark the desired cut line in the tube.


At this point the tape can be removed, revealing the line to cut.


And voila, a finished tube!


Lather, rinse, repeat.



I knew from the start that this method might provide slightly less accurate cut positions and angles than I get from my hand calculations, but it proved to be quite a bit more accurate than I had anticipated.  I was impressed with how easy this technique was to get a feel for, as well as how little 'massaging' will be require to finalize the tube fitment.  Just remember that it's a LOT harder to cut material back onto the tube, than it is to cut more material off.

Sunday, October 19, 2014

SWMBO

Somehow the acronym SWMBO (She Who Must Be Obeyed) never really seemed appropriate for my wife, so I gave her the much more deserving title of SWEETA (She Who Enables Every Thing Automotive).  Maybe it was a coincidence, and maybe it was a premonition.  There is no way to know for sure.  What I do know is that with a baby girl in the house there is one, and only one, SWMBO...And it certainly isn't my poor SWEETA.

 As weeks turned into months of virtually no progress, in the back of my mind I did start to wonder when I would ever be able to get back into the swing of things with this build.  Fortunately, SWMBO has appears to have recently approved my request to exchange the previous weekend mornings for weekend nights, by regularly falling asleep considerably earlier.  Additionally SWEETA has given this new schedule her blessing as well, by also choosing to go to bed at that time.  Thus, for the past 4 weekends in a row I have gotten garage time!

Unfortunately, I have spent more time that I care to admit relearning some of the things that I was doing without giving a second thought before SWMBO arrived.  Consequently, I have also spent far to much of this precious time redoing said things...Often more than once.  As of this weekend, it feels like it's all starting to flow again though.

Current progress is limited to having tacked in the tubes from my last update, and having cut the 4 additional tunnel diagonals sitting in the chassis as pictured below.  Yes the chassis as pictured is currently up on its side, so that's three bottom diagonals and one upper diagonal.


Tuesday, August 5, 2014

Finding Time

With the recent life affirming changes affecting my priorities, I think it's going to take some time before I'm really able to get back into a consistent pattern of both progress and updates again.  It's also that busy time of year for other activities and obligations filling our weekend schedules.  Another month has passed since my last update, but I am pleased to say that there has been at least some continued progress.

Three weeks ago I managed to get a handful of tubes cut.  The long pair with the angled ends are the forward top tunnel tubes, the mid length pair with the squared ends are the vertical tubes on either side of the transmission at the firewall, and the short pair with squared are part of the top and bottom transmission tunnel reinforcement.  My next update should be of these tacked in place.


Two weeks ago was a mini-meet of local homebuilt car (Locost) enthusiasts.  There were two with completed cars that showed up, and two (including myself) that are still slaving away in our garages.  I've seen the proof with my own eyes, that these cars CAN be completed!


And one week ago I picked up potential steering rack, as this will be a critical component in designing the front suspension. The most readily available aftermarket production-based racks are probably the Ford Mustang units, which works well with my Ford component theme as well.  It would seem that similar critical dimensions can be had with the right outer tie rod end selection on Mustang II, Fox Body, and SN95 chassis Mustang steering racks.  I've been looking at dedicated manual racks, as the depowered Mustang racks seem to get significantly more negative reviews than positive.  The Mustang II manual racks are simply too slow at 1.3 to 1.4 inches of rack movement per turn of the steering wheel.  The aftermarket manufacturers have "quick ratio" manual racks for the Fox Body, but they're still a bit on the slow side at 1.6 to 1.75 inches per turn and keep nudging the budget up.  The SN95 never came with a manual rack from the factory, but also has a similar "quick ratio" aftermarket manual rack that seems to do little more than use different thread pitch tie rod ends and add cost over the Fox Body Racks.

However, I do also know that depowered racks are popular with Miata drivers and typically get positive feedback.  So I when I came across an OEM power rack for a Fox Body Mustang at the right (low-cost) price, I jumped at the chance to buy it.   Before making any final decisions on the front suspension design, I will be attempting to disassemble this rack to get a good look at the internals and determine what modifications might be possible to use it successfully in the depowered state.  A preliminary check show that the Fox Body power rack appears to have ~2.2 inches per turn.


Sunday, July 6, 2014

Changes

"Nothing endures but change" - Heraclitus.

It's been the better part of two months since my last update.  This weekend was my first chance to get back to working on the car.  All necessary holes for the floor diagonals were drilled, patterns were taken from the floor diagonals, and all of the floor diagonals are tacked in place now.


There is actually a very good reason for lack of progress though.  Big changes have been happening around here, and I have embarked on a new 'project' in the weeks since my last update...

They say that good help is hard to find.  I'm not sure who "they" are, but I need all the help I can get on this project.  So in the Locost spirit, although anything but low-cost, we’re making our own helper.


It has already become apparent though, that she's the boss and I'm the helper.

Sunday, May 18, 2014

Flooring

 
In my last update I had cut and fit two tubes in two weeks.  This past two weeks I cut and fit 8 more tubes.  It's hard to complain about a 400% increase in productivity!

Tuesday, May 6, 2014

Floor and Tunnel Decisions

Two weeks have passed since the last update, and as many tubes have been fitted in that time. 



Before I could decide on how much to angle the forward portion of the tunnel into the foot well space, I needed to track down and pick up a "backup light switch connector" from one of the local auto parts stores.  That little plug is the point of greatest interference on the driver side of the transmission.  After mocking it up different ways, and spending more time than a grown man has any right to sitting on a table pretending to drive an imaginary car to 'get a feel for it', a decision was made.  It'll be tight, but by offsetting the transmission (and engine) slightly to the passenger side I should be able to get away with only a 2 inch taper on the driver side.  That will still leave me with a generous 15 inches of foot well width for the driver...The passenger will have to make due with a bit less.  That left me with just enough time to fit the lower tube that weekend.

This past weekend I spent some time sketching out a few options for diagonals across the floor pan.  I settled on one that will allow the same diagonals to be used on both sides of the chassis, and should do a good job keeping my sensitive areas well separated from the pavement.  I was only able to get around to fitting one of these tubes.  But with a plan in place, the next series of tubes should be able to follow a bit more quickly.

Sunday, April 20, 2014

Vroom Vroom

As I sat in the chassis contemplating how to proceed, I couldn't help myself.  I had to take the obligatory "vroom-vroom" pics:

Heading down to the local cruise night.

 
Chasing a Corvette through "The Kink" at Road America.

Visual Progress

This weekend started out with more unconventional jigging.


Once the tubes were all tacked in place, I had to try to figure out how to get the damn thing flipped and rotated to a more useful position.  Needless to say, it doesn't look like I'll be able to maneuver the frame around for very much longer, without the assistance of my hoist.  I would dare say that it's almost starting to look like a real chassis.


One decision I've been mulling over, is how to build the upper portions of the foot wells in such a way that the transmission can be reasonably installed or removed.


As you can see, the shifter stub protrudes up a bit and will probably require a considerable amount of jockeying to get it in and out even as shown with the transverse tube an inch higher than it would ideally be.  One alternative is that once the final transmission tunnel tubes are in place, any tubes in the shifters path be removable.  Eliminating them might work, but would be less elegant as it would require 'creative' bracing for the load paths to return to the tunnel behind the transmission.  Getting the forward tunnel tubes cut and put in place should give me time to formalize a plan of action.

Sunday, April 6, 2014

Driver Side Tacked

With preparations for the arrival of our "garage helper" kicking into high gear, my typical garage time has been increasingly filled with more important projects and events.  Not the least of which included my solemn duty to keep some of the other 'shower' husbands occupied with a local wine, beer, and whiskey tasting tour.  However, I had a break this weekend that allowed me to make some good progress.

It began with cleaning up my workspace from the other projects that had accumulated over the past two weeks.  Following that, the next 12 tubes were cut and trimmed to length, cleaned, and prepped for installation.  This morning I constructed my somewhat unconventional jigging of the chassis, that actually held everything surprisingly true according to my carpenters square.


A few conveniently placed tacks later, and the driver side is officially in place.

Sunday, March 9, 2014

Tunneling

As usual, no matter how realistic you believe your goals to be, progress typically occurs at somewhere between 1/2 and 1/3 of the anticipated rate.

Since my last post I've been making progress, but nothing terribly interesting to take and share photos of...Not that most of my photo updates thus far have been overly 'exciting' either.  I spent some time finish welding the second two chassis rails.  Then some more time mocking up the chassis rails while debating between 17.5" wide seats with a 8" wide tunnel, 17.25" wide seats with a 7.5" wide tunnel, or 17" wide seats with a 7" wide tunnel.  And finally this weekend, making the transverse tunnel tubes and prepping the two tunnel rails to be mated together.

To ease any potential issues with the differential pinion being offset to the passenger side, in addition to focusing on my personal seat width, I decided to keep moving forward with the originally planned 17" wide seats and 8" wide tunnel.  As with every other decision, this has both advantages and disadvantages vs the alternatives...But all minor relative to each other, as well as in the big scheme of things.

Everything is now prepped so that next weekend I will be almost certainly be going "3D" with at least a tacked up tunnel.  I hope to get even further, but I'll direct you back to my first statement in this post.  The last decision to make before doing so, is how I want to install the transverse tubes that will make up the bottom of the rear firewall.  Options "A" and "B" are shown below...But I'm also considering secret option "C" with some type of hybrid between the two shown by using additional portions of tubing or gusseting.  Obviously this is one of the more 'detail oriented' decisions that will make little difference either way, but it does give me a little something to ponder until next weekend.



Monday, February 24, 2014

Chassis Multiplication

So that's what happens when you leave two sections of chassis alone in the garage together!...


Sunday, February 16, 2014

Sharpies

Mental note: Industrial Sharpie is almost as tough as mill scale. Acetone barely fades it. Stick with Original Sharpie for marking welds on Steel.

Sunday, February 9, 2014

Chassis Tube Templates

With the mill-scale scourge defeated, I'm almost ready to actually be productive again.  I have but one mental block to break through before welding up the remaining two sections of cut chassis tubes.  The amount of time it took to produce the second identical set of, now welded together, tubes was a mere fraction of the amount of time it took to produce this first set that I'm now finally preparing to weld together.

As my skills grow through the process of building this chassis, so too will the quality of my workmanship.  I am confident that my fabrication of this chassis will be more than adequate for safely cruising around town or hitting the local autox.  But I do also want to take this car to the race track, and I'm not yet sure of my confidence level in this same fabrication when traveling at speeds well into triple digit speeds...But I need to find a way to keep moving forward if I ever want to get this car on the road.

I also know that as much as I'd like to make it look like I can design everything perfectly on the first try as I go along, I know that I will have to make changes to previously 'completed' work, as well as there will be things I wish I had done a bit (or a lot) differently when seen in hindsight.

So to assuage my fears and bring me the inner peace I need to proceed, I am making templates of every tube.  These will allow me to build a second chassis with relatively minimal effort, if at any point in the future I see fit to do so.

It's actually a quick and easy process, the hardest part of which was finding a suitably sized and priced material.  I happened across 5/8 vinyl J-channel for cheap at my local hardware store.


Using a utility knife, score down the full length of the inside corner on the shorter side.  Fold the short side "open" to lay flat with the base, which will cause the vinyl to fracture along the scored line.  Then peel the short side off leaving a vinyl L-channel.


Orient the tube into the L-channel as necessary, use a sharpie to mark the tube end profiles, and cut with a tin snip to match.  Lay it back over the tube to verify the angles and lengths are correct.


And before you know it, you've got a whole family of templates.


Note that some are simply numbered, while others have "A" and/or "B" associated with the number.  As usual, there is a method to the madness. Due to my band saw only being able to make angles in one direction up to a 45 degree angle, numerous tubes needed templates that either oriented a specific way or needed one template for each side.  It takes a bit of thought to get them all sorted out the right way, but apparently is nothing that the average idiot who thinks he can actually build a car from scratch in his own garage couldn’t figure out on the third or fourth try.

Sunday, January 12, 2014

Mill Scale Sucks

So far I have gotten two batches of steel tube.  The first was ASTM A500 and the second was ASTM A513.  Each was all they had in stock for 1x1x0.065 tube at the time.  So what's the difference, besides about 13 whatchamadingers?  In terms of mechanical properties, not enough for me to worry about.  They're both pretty standard hot rolled, seam welded steel tube.  However, at least as stocked by my steel supplier, the A500 was protected by a light mill scale...Where as the A513 was cleaned and protected by an oily residue.  Then which is better?  During initial handling, neither is great.  The A500 leaves black grime on everything it touches, and the A513 leaves oily residue on anything it touches.  However, the oily residue cleans off easily with a quick wipe down of Acetone.  The same cannot be said of the mill scale.

One of the popular ways to rid yourself of the Mill Scale plague, is by using a diluted acid solution, which can cause all manner of hazardous material problems that I have absolutely no interest in dealing with.  To mechanically remove it though simply takes time...Much more than anybody wants to spend doing it.  Some people simply do a half-assed cleaning of the tube, while only doing a whole-assed cleaning where the welds will be.  The idea is that the mill scale is well adhered to the tube, and there are paints that at least adhere well enough to the mill scale for it to not be a problem...But if you couldn't tell from my previous tube prep on the A513, I'll be doing it the complete and total assed way.

As seen in the picture below, at the top is the original flat black mill scale wiped of the initial loose grime.  Below that is the 'half-assed' cleanup.  This is a few lighter passes with a wire wheel, and has basically polished the mill scale to kind of a satin black.  The bottom shows the fully cleaned up steel, after numerous heavier passes with the wire wheel.  Off to the right, you can see the pile of tubes in the semi-finished state, and the one tube on the left that is fully-finished.


So if your steel supplier tries to sell you on tube with mill scale...In the immortal words of Bing Crosby, "don't think, don't pause, don't hesitate for a moment, just spit in his eye."

Monday, January 6, 2014

Weld Sequencing

As with anything else, the more welding I do, the better my welds are becoming.  It also means I'm figuring out those little tricks that create significant improvement in various specific welding scenarios that you don't even think about until after throwing yourself into those scenarios.  By the time I'm done with the chassis, I might actually make a half way decent welder!  Of course in the mean time, this means I get to look back on all of the welds up to the point of each new revelation and try to force myself not to simply start over.  It may however mean that the earlier sections of chassis will be getting a little additional gusseting...Just in case.

On the other hand, my overall results have been good with keeping weld distortion to a minimum so far.  After tacking the section all together, I pull it out of the 'jig' so that I can flip and rotate it around into whatever position will allow me to reach any given joint the most easily.  My technique starts off with welding all of the fillet welds on the inside corners for the main boxed segments first, alternating corners around the chassis.  Then doing the same with the outside corners.  After that is the fillet welds on all of the diagonals.  And last comes all of the the butt welds on either side.  Really the primary source of what distortion I have seen appears to be coming from any minor variances in tube fitment.  Wedge a tube in too tight, and when welded it bows the tubes on either side out.  Leave a little gap, and the weld will pull it closed.  None of this shows up well in pictures though.

However, I do have a picture illustrating one other method I'm using.  I find the hardest to reach weld for every tube joint, and figure out what position both of us (the chassis and myself) need to be in to most easily weld it.  This includes determining which direction the weld will go.  I then mark that next to the joint.  Every other joint around that tube intersection is then welded moving the same direction, such that the coldest part of the weld at the beginning overlaps the hottest part at the end of a previous weld.  Alternatively the hottest part of the weld at the end overlaps the coldest part at the beginning a previous weld.