1/16 Scale RC Truck parts

[tom osselton]

  I’m watching too.

[ddmckee54]

A little more progress has been made.  I was able to find the broken stub that was shown in Post #18.  I thought that I had pitched it, turns out I'd just misplaced it.  I found it when I went to use the toaster oven to remove the gears from the next donor axle.  I have enough bits and pieces that I now have the fixin's for 2 complete differentials, if I can get that M2 screw with the rounded out hex removed.  While the toaster oven was hot I also took apart the axle shown in Post #20 that was 4mm too long.  At some point over the last several years I had purchased the smallest Easy-Out I've ever seen.  I was able to get enough purchase with it that I could back the screw out enough to grab on to it with a pair of pliers and remove it.

Today I modified the stub axles that I already had cut apart.  The axle shaft from Post #20 was 74.27mm over-all in length, so I'm aiming for a 70.25mm length in my completed axles.  I modified the first axle, Loctited it together, and left it clamped in the Vee-block while I modified the other axle. 

One measures 70.14mm, and the other is 70.38mm.  Not bad for a beginner, but I plan on doing better next time.  And, the only thing that I had to scrap was that bent length of brass tubing shown in Post #18.

[ddmckee54]

The axle looks good, but when I transferred the duals from the Kong axle onto my axle... the wheels sorta fell off the bus.  When I tightened them down they wouldn't turn.    I took things back apart and started measuring bits and pieces.

The 12mm hex driver from the Kong axles is 6.5mm thick and uses a drive pin with a 1.5mm OD.  The WLToys hex driver is 5.5mm thick and uses a drive pin with a 1mm OD.  I backed things off enough that the wheels turned freely and did a sanity check against the Bruder tires.

From this angle things look OK, however...

From this angle you can see they're too narrow by a couple of mm.

If I make the driver pockets 5.5mm deep instead of their current 6.5mm depth then things should be just about right.  I think I'll make the pockets 5mm deep though, because a little clearance nerver hurts Clarance.

[ddmckee54]

Progress in the last couple of days has been a lot like doing the Hokey-Pokey, one step forward, two steps back, and three steps forward.

I modified the existing 3D model for the dual wheels to correct the hex pocket that was too deep.  To do that I  had to roll back through the history tree and modify the step that formed the pocket, changing the pocket depth from 6.5mm to 5 mm.  At this point it was almost bed-time, so I did what any sane person does and spent the next couple of hours watching YouTube videos - THEN I went to bed.  The next day I saved and sliced the STL file and started the wheels printing. 

About 3 hours into a 4 hour print I noticed a alarming lack of features in the print and promptly aborted it.  There  SHOULD hove been 8 holes for the M2 screws that hold the hub cover on, and there were also supposed to be 8 slots in the rim that were suspiciously absent.  When I saved the STL file I hadn't rolled the history tree back to the end, so the STL just included the 3D model up to that point in  the history.  It skipped a couple of important steps. like the screw holes, the slots, and most importantly - scaling the model for printing.

Once I corrected the operator blunders, I really gotta hire better help around here, I reprinted the wheels.  This time things worked out like the should have the first time.
 

Other than black wheels instead of red, it doesn't look that much different than it did in the last post.

[vtsteam]

It was the YouTube videos. 

[ddmckee54]

Yeah, about Plan B....

It turns out that when I reduced the depth of the hex pocket in the rear wheels I reduced the wheel track at the same time.  This would have caused problems down the road because it also reduced my already minimal tire clearance to the frame rails.  The "Bag of Misfit Parts" continues to grow.

For the last couple of days - ish, I have been working on adapting an idea for a powered steer axle that I stole from Blender on another forum.  I've now got it to the point where I'm putting a front diff  assembly together in Alibre to check the fits.  It looks like about the only modifications I'll have to make to the diff housing models is to turn off the step that forms the pads on the outboard ends of the housing halves.  I think I found some Nylon flanged bushings and shoulder bolts on Ebay that I can use for the pivots on the knuckles.  I'll have to verify sizes, get some ordered, and modify the 3D models to suit.  I've got a lot of clean-up work to do on the models before they'll be printable.  When I can remember, or figure out again, what I did/need to do to show the suspension assembly I'll post what that assembly looks like.  I got a 3D model of what would probably be the shortest 1/16 scale 6x6 truck frame and a Hendrickson style walking beam rear suspension.  So far it LOOKS like everything will clear without major issues.  I've just been working on the driver's side of the front axle, but once I'm happy with that, mirroring the parts to the other side is simple.

Speaking  of printing, Ebay made me a offer on a certified re-furbished Creality Mage S printer that I couldn't refuse.  So I am now jumping down to resin printing rabbit hole - wish me luck.

[kayzed1]

  me too!

[ddmckee54]

I mentioned in an earlier post that the ER16 chuck I got for the Sherline mounts in the spindle's Morse taper and uses a 1/4-20 bolt for the drawbar.  I know that this will give me better concentricity, but the work I'll be doing in the foreseeable future doesn't require that level of accuracy.  Besides, I really like to be able shove a long-ish part through into the spindle bore; like a 102mm long donor axle that needs to be shortened.  So today I went searching for another ER16 collet chuck for the Sherline's 3/4-16 spindle threads - I didn't find any.

I DID find one for a Taig lathe though, and I also found out that since they both use the same 3/4-16 threads on their spindles it will work just fine on the Sherline.  Since the price seemed reasonable I arranged to get one headed my way.  I also ordered some other little doo-dads that I'll be needing in the near future.

Getting the suspension assembly into a format useable on here was easier than I remembered.  Alibre allowed me to export the assembly as a JPG file.  I then used Gimp to scale the image to a 640x480 format that most forums will accept.  Then it was saved to Google Photos since a lot of forums require you to use 3rd party storage if images/videos.  Annndd... you get something like this.
 

I know it's missing a lot of stuff, a couple of wheels, ALL the tires, drive shafts, fasteners, tie rod, not to mention the great gaping hole on the passenger's side where the pivots, steering knuckle, and CV joint should be.  Cut me some slack, this is a Proof-of-Concept model, not a for-realsies highly detailed 3D model.

[ddmckee54]

I just finished modifying the second set of donor axles.  They look remarkably like the first set, just a little more consistent.  One measures 69.95mm and the other is 69.97mm, I was aiming for 70.00mm - so I'm about 2 thou under with both of them.

I've still got some issues with the Sherline, the headstock bearings are stiff and kind of rough.  They have been since I first started working on it.  I suspect that the original grease in the shielded bearings has dried out.  I've been dousing them with light oil in hopes of reconstituting the original grease but so far no luck.  I'm thinking it's probably going to need new bearings.

The other issue is with the carriage lead screw, it binds up.  However I only notice this when moving the carriage towards the headstock, and it only binds up when the handle is between about the 2:00 and 5:00 positions; the rest of the time it's OK.  I'm thinking that when the Sherline did the nose-dive off the bench onto the drive dog for the threading attachment it left a boo-boo that I didn't find during the initial repair, which happened about a month before I started this thread.  The ham-handed retired engineer that managed to knock it off the bench should have had his wages docked for the repairs, but since he doesn't get any wages docking them is kind of an empty threat.

[vtsteam]

Sorry to hear about the lathe accident!  Sounds like a bent lead screw. Maybe up near the handle. Any chance of taking it off and straightening? 

[ddmckee54]

Hmmmm...guess I didn't show what the modified axles look like.


Regarding the Sherline carriage lead-screw issue, when I started taking it apart last night I discovered that the issue went away when I took the hand-wheel off.  Upon closer examination of the hand-wheel and the lead-screw shaft I found a nick on the face of the hand-wheel and a burr on the lead-screw.  The burr on the lead-screw was caused by the grub screw, but I've got no idea what could have caused the nick on the hand-wheel.  I stoned off the raised areas and when I reassembled things that particular problem was gone.

I've been plottin' & conivin' for a while as to how I can adapt the Frankendiff into a powered steer axle.  Blender's build of a 1/14 scale TH407C telehandler on another forum gave me the idea I needed. He used Losi CVD front axles to build his steer axles.  Since I've already got a butt-load of the WLToys 12428 replacement rear axles I decided to get a set of replacement front axles to see if they'd be usable.  After doing a little (very rough) 3D modeling, it looks like things will work out.  They both use a ball and socket joint in the knuckle, but the Losi uses a CVD joint while WLToys uses a CVA joint.  A CVD joint has the ball on the axle with the socket on the half-shaft.  A CVA joint flips that around and has the ball on the half-shaft with the socket on the axle.  Here's a picture of the WLToys CVA joints.


At the top is the assembled CVA joint, in the middle is the axle with the socket, and on the bottom is the half-shaft.  At the left is the dog-bone that would normally attach to the front diff.  This 14mm section on the left is totally useless to me, I only need about the last 25mm on the right.  The center section of the half-shaft currently has a 3.18mm OD.  My current plan is to turn part of the center section and part of the tapered area just to the right of it down to a 3mm OD.  This will then be Loctited into the outboard end of the modified donor axle, just like I did when shortening the donor axles for the rear diffs.

[ddmckee54]

The Sherline bearings are supposed to be lubricated for life, but they are shielded bearings - not sealed.  If they sit for several years without being used, the grease will dry out and harden.  According to the part number they are standard precision bearings, not high precision.  Once upon a time in the west I used to repair machine tools for a living, so swapping spindle bearings is not outside my comfort zone.  At least now the parts are a LOT lighter, and they're not covered in congealed nasty smelling coolant.

Yesterday I modified  the first CVA half-shaft.

The modified half-shaft is just slipped into the brass tube for now, I'm just getting started on the working 3D model that will be used to print the parts.  I've got bushings and shoulder bolts on order for the knuckle pivots, so I can accurately model things now.  I model things in mm because that's how most 3D printers think.  I really wonder sometimes when reverse engineering this stuff, because some of the measurements make no sense.  Like why is part of the half-shaft turned to 3.18mm, and why is the socket bored to 7.62mm.  Earlier today it finally dawned on me, 3.18mm is 0.125", and that odd 7.62mm bore is 0.3".  When I convert all the oddball Metric measurements to Imperial units they come out nice and neat.

[vtsteam]

I hear you, dd, on the tediousness of units conversions, but that .3" seems unusual even for imperial, where you'd expect .3125". Wonder where that came from? 

[ddmckee54]

I hear you, dd, on the tediousness of units conversions, but that .3" seems unusual even for imperial, where you'd expect .3125". Wonder where that came from? 

Who knows, maybe it's just a coincidence.

I'm brain-fried right now, for the last 5-6 hours I've been fighting with Alibre locking up.  I'm trying to do the final 3D design for the powered steer diff parts.  The design I showed a couple of posts ago was thrown together to see if I could even make it work.  NOW I need to cross the I's and dot the T's so that it will all work together, and that means modeling all the individual parts.  That's actually a good thing as I found a couple of gotchya's while doing it. 

One of those gotchya's was determining how much I needed to shrink/stretch the ends of the diff front and rear housings to accommodate the single front wheel instead of the dual rear wheels, and still maintain the same wheel track.  It turns out I needed to take 13.5mm off each side.  I know that doesn't make sense that I need to move the end of the diff housing inboard when going from duals to singles, but I spent a couple hours convincing myself that moving things 13.5mm inboard was actually right.

The second gotchya was when I realized that the screws holding what I'm calling the diff pivot in place would be hitting the outboard bearing - that would not be good.  So I had to change the design of the diff pivot, it's now about 6mm longer.  THIS change interfered with the outboard screws holding the front and rear diff halves together.  Since the diff pivot slides over the ends of the front and rear diff halves holding them together, those screws aren't really needed any more.  Problem solved, but I did have to change the 3D models for both halves to reflect this.

The third gotchya is what does the length of the brass tubing splice need to be?  My modified rear axle measures 147mm from end to end.  My modified axles were 70mm nominal length, so that means the spider gears were occupying 7mm of space in the middle.  My 3D printed non-powered front axle is 172mm from end to end.  If I subtract the 7mm for the spider gears, and divide be 2, the stack-up for my front axle length should be 82.5mm?  (Why do I feel like Rodney Dangerfield in "Back to School" right now?)

While typing this I just realized that there's nothing keeping the outboard bearing of the front axle from sliding outwards.  On the rear axles the hex driver holds the bearing in place, on the front axle there's nothing but air in that location.  Oh well, that's a problem for future me, right now it's time to call it a day.

Don

[RussellT]

It's always puzzled me  (well since I found out about it) why Nato standard ammunition is referred to as 7.62mm when it is 0.3 inches.

Russell

[vtsteam]

I suppose if you want to finish off 5/16" hot rolled stock, .300" might be a convenient figure to shoot for.

[ddmckee54]

I'm still fighting with Alibre Design Pro, I just purchased a perpetual off-line license about 6-8 months ago.  I was using Designspark 3D Mechanical until they went subscription.  I know they still have a "Free" version, but that version is a dumbed down copy of what was current before they went subscription.  I haven't used Alibre enough to become proficient with it yet, especially when using an "assembly".  I can put the parts where I want them, but when I try to animate the parts things start to go hay-wire.  Also, with the suspension assembly shown below I'm trying to build it out of various sub-assemblies.

The suspension assembly contains sub-assemblies for the rear axle, the center axle, and the front axle.  When working directly with the front axle assembly I can make the CVA axle pivot like it's supposed to.  When I add the front axle sub-assembly to the suspension assembly I can no longer make the CVA axles pivot, there's probably check-box somewhere that I need to check/un-check - but I haven't found it yet.  When I get the spindles/axle bearing housings/steering arms, and the tie-rod, designed it will be interesting to see if it will act the way it's supposed to. 

[ddmckee54]

I think that I just might be starting to get a handle on this Alibre assembly crap. 


You are looking at a functional 3D assembly model.  I can spin the wheel on the axle.  When I turn the steering knuckle the wheel moves with it, and the tie-rod brings the knuckle on the other side along for the ride.

I did have to give up on the idea of putting the tie-rod above the drive shaft though, there just wasn't enough room.  Where it is currently located the tie-rod is about 4-5mm below the driveshaft and won't touch any thing trough its' full range of travel.  The bottom of the tie-rod is still above the bottom of the differential though so the tie-rod shouldn't get caught on any thing.

[ddmckee54]

I've been working on the Sherline again for the last week.  I'm replacing the cheap Chinese scales that I put on it a couple of months ago, they were just an experiment anyway.  I didn't know if I like the scales, and I didn't know if a Noob like me could get them installed without destroying something.  I got them installed, and that was a game changer for me.  I REALLY like the idea of scales on the lathe, just not those scales - for several reasons. 1) They're battery powered, and there's no provision for an AC adapter.  My scales have no Auto-Off feature, I don't know how many times I've come down to the shop only to discover I'd left the scales on the night before.  2) My carriage scale periodically resets to 0.  I've found that this glitching is not an uncommon problem with these scales.  One one the ways they can make them so cheap is by eliminating all the shielding.  3) I really don't like the way I installed them.  I used the brackets provided with the scales which meant the scales wound with the scale facing up, as a shelf for chips and dirt.

I'm replacing the cheap scales with Igaging EZ-View Plus scales, they've got better resolution, they're shielded, and they have an available AC adapter.  I was having trouble wrapping my head around what the brackets for the new scales should look like, and if the way I wanted to install them would even work.  I spent the last week building a 3D model of my lathe, the base it sits on, the carriage with its' dovetails, the cross-slide with its' dovetails, the new scales, and the new read heads.  I then put all those parts together as an assembly drawing and got the carriage and cross-slide working together and set the limits for their normal range of motion.  I initially had the scales and read heads just hanging out in mid-air.  Once I got things dancing around together I started designing the brackets that would hold things together holding the various bits and pieces in place.  The 3D model looks like this, all the pinkish bits are 3D printed parts.


Last night I started the 3D printer pooping out the parts before I went to bed.  This morning these were waiting on the printer for me.

Unfortunately the part in the upper RH corner, and part in the lower LH corner do not fit.  Operator error, what can I say.  I fixed the model and re-printed those parts.  The installation is ongoing and should be complete tomorrow?

[vtsteam]

Don with those scales you might like to check this site out:

https://www.yuriystoys.com/

I use the bluetooth DRO on my mill, as detailed here.

https://www.madmodder.net/index.php/topic,13501

VERY happy with it. Also I could use the same box with my lathe if I did add scales, and just unplug it from the mill and plug it in there. 

[ddmckee54]

I've been keeping an eye on Yuri's work for a number of years now.  The last time I checked, he'd found out that the Igaging EZ-View Plus scales use a different protocol than their Digi-Mag scales did.  He was working on an interface but it wasn't ready yet.

[ddmckee54]

Further development on the is on hold for a week or so.  The motor/2-speed gearbox, that I initially wanted to power the model with, uses a single 370 sized motor and has 3mm output shafts.  While the 370 sized motor MIGHT have been up to the task, I don't think the 3mm output shafts would have been - since all of the differentials have 5mm input shafts.

I've got an LDRC LD1201 Unimog replacement motor/gearbox ordered.  It uses a pair of 370 size motors driving a 2-speed gearbox with 5mm output shafts.  One of the outputs looks to be centered, and the other appears to be offset to the side.  If it is offset then I'll have to slide the pumpkin to one side on the front and rear housings for my steer axle.  Unless I can find some drawings on-line, I won't be able to do any more work on the steer axle until I can get some measurements from the gearbox.

[ddmckee54]

The motors/gearbox/transfer case arrived today, now I'll start 3D modeling it.  That way I can use that model to design the offset I'll need for the pumpkin in my steer axle.  I'll also have that model for use in designing the parts for the future conversions.  The output shafts are 4mm, not the 5mm I had hoped for, but they can easily be bushed up to the 5mm needed by the differentials. 

I was worried that there wouldn't be enough room for the Universal joint to the front axle.  The dimensions for the drive shafts I'm looking at say they're 12mm in diameter.  The only way I could get a measurement to the obstruction was by measuring across the shaft to the obstruction, and that distance was 8,55mm.  Since it's a 4mm shaft, that means the obstruction is 6.55mm away from the center.  The drive shaft needs 6mm, so I SHOULD have at least a half mm of clearance.  And clearance is clearance Clarence.

It also looks like I'll need to make custom drive pins/set screws for the drive shafts, but that'll be nothing more than turning down some 4mm set screws to fit.  I'd better get some 4mm set screws on order so I've got something to work with.  It's real IFFY that the local hardware store would have any.  I have trouble finding anything smaller than 6-32 in Imperial and 5mm in Metric.

Don

[ddmckee54]

Between a late night last night and some more time this morning I got the motors/gearbox/transfer case modeled.  I measured the wheelbase between the front axle and the center axle in the MAN mixer and extended my frame rails accordingly.  I dropped the motor unit into the assembly model and got it positioned about where it will live.  The assembly model now looks like this.


This thing is starting to look more like a truck, and less like a clown car.  The frame rails are 335mm long now which is probably about right for a 1/16 scale cab-over.

I COULD move the front diff's pumpkin 18.5mm to the passenger's side, which would get the  transfer case output shaft and the differential's input shaft lined up side to side.  But, if I do that then the pumpkin is going to be crowding into the area that the knuckle pivot needs to live.  So I'm only going to slide it over 10mm.  The drive shaft angles will be a little harsher, but it's not like I trying to design these for thousands of miles of useful life.

[ddmckee54]

OK, a couple of minor speed-bumps, but nothing that Ebay and a credit card can't handle.

Speed-bump #1 - Most of the drive shafts I've found have 5mm bores or 6.2mm bores. The WLToys axles have 5mm input shafts and the shafts with a 5mm bore are a better fit to the LD1201 transfer case. But the LD1201 has 4mm output shafts. No problem, I'll just cut a piece of 4x5mm tubing and glue that into one end of the drive shaft. "Cept that I ain't got no 4x5 tubing, I've got 3x4 and 3x5 - but no 4x5.

Speed-bump #2 - Drive shaft lengths. I can't really find the drive shaft lengths I need. My last revision of the 3D model for the suspension/chassis put all the axle spacing's in their correct positions for the upcoming cement mixer conversion. I also centered the gearbox so that the front and rear drive shafts can be interchangeable. This leaves me with a nominal drive shaft length of 46-ish mm. Since the transfer case output shafts are 2 different lengths, 6mm and 7mm, I'm using the 7mm length to determine the minimum and maximum drive shaft lengths. I need to collapse my 46mm nominal drive shaft about 7mm in order to be able to remove the drive shaft - without needing to remove other bits of the truck anyway. I also need to allow for suspension droop, which won't be much since this is a cement mixer - not a rock crawler. But I need to allow for some, so I'll use 7mm there too. Bottom line - I need the front and rear drive shafts to be from 39-53-ish mm in length. It can be more than 53mm, but no less. The drive shaft from the center axle to the rear axle is worse, it needs to be from 33-44mm in length. These are the drive shafts that I like the best.  https://www.ebay.com/itm/375169557748

But....The shortest length is 60-77mm, I've got 3 of them on order. On the plus side, they use an internal/external spline for the extension instead if a square drive or a pin in slot setup. The external splines are full length, they are easier to cut so that makes sense. The internal splines are not easy to do at this size. That difficulty goes up as the spline length increases, there's not that much room in the hole to begin with and the chips HAVE to go somewhere. My guess is that the splines are only a few mm in length, the rest of the hole will be counter-bored to the major diameter of the splines - if not larger. My current plan is to cut a big enough chunk out of the middle of the female half that the length of the stack-up equals my minimum drive shaft length. I've got some 3/8" OD aluminum tubing that I'll use as a reinforcing sleeve and glue the cut parts into it. Then I cut the male splines off just enough to allow the drive shaft to fully collapse. And Bob's you uncle - I hope. It worked for the axle shafts, should work here too. We'll find out. I also ordered 2 of these. https://www.ebay.com/itm/314228515981 To see if I can cut them shorter than the others for the center to rear axle shaft.

If I get REALLY lucky, and the internal splines go full depth, then all I have to do is cut things to length. (And if you believe that's gonna happen... Well, I got some bottom land in Florida I'll sell you - it's REAL close to the river.)

Don