Hirobo 44Bs and Zerda :)

[silvertriple]

Parts arrived today around 3pm. I had to wait until my work was over to start looking at the printed parts...

My main concern was the chassis. I was worried as there was clearly a risk of deformation. That being said, if I need to do something about it, I need to understand what deformation we are talking about...

It's here, so now, I know.




And de facto, there is some deformation. This being something I should worried or not is a key question... But before trying to respond here, let's look at the rest...



Yes, all plastic parts were 3D printed. I also printed 2 set of front hubs (one is for 44B, because I forgot to remove it from the order - I might have to key another order to build a 44B next ).



Now, trying to answer the key question :


First, only the chassis is having some deformation. It's not as bad as I thought initially. Belt cover as no deformation at all. Roll cage parts seem fine as well (MJF printed, I will do a black cage, after all, this is a kit). Another indication is that when I put the central part of the roll cage in the chassis, the chassis is getting back close to the expected shape, and it is not yet fixed together with screws... I would expect that once everything is in tension, it should be fine and more or less in shape...

Last question I will need to answer : should I keep the parts white or should I color them. And if I color them, should I color them red of something more unusual?

[silvertriple]

Now that the printed parts are here, I had to complete the set of parts to be able to make this Zerda...

I ordered this morning a few parts
- GT2 pulley 18T bore 5, GT2 pulleys 14T, 16T, 17T, 18T in bore 3.125 (I could not find any 15T, so it will have to wait)
- rods in 5mm to make the transmission shafts
- rods in 2.3mm to make the suspension shafts
- rit dye orange apricot to make a distinct non white color for my parts

Belts are already there, as well as HBX wheels shafts, 56mm dog bones (I have the reference somewhere), ball bearings, pivot balls, 3mm rod and associated rod ends (the same as the one I already used for the 44B Hilux with FDM printed parts), optima re-release differential innards...

Regarding the way to deal with the rods cutting and modifications, the plan is to rely on my dremel, a vice, a dremel drill press and printed parts to make the cuts, holes, flat areas and groove at the right place... Maybe I'm too optimistic, but it should work

Last elements are going to be last few parts I will need to get printed, and there is a reason why they are not printed yet: the intension is to make those at some point, conjointly with the upper deck which needs some further thinking as it is what should rigidify my Zerda...
And another element I need to plan for : out diff drives. I have 4 original Hirobo parts sitting in my parts bin, but I'm not willing to use those. I'd like to find a proper solution so I can say my Zerda have not a single original Hirobo part... I know that an easy way would be to use some Optima original parts for this, but the idea is really to use a part widely available in nowadays range...

[silvertriple]

It is time to figure out something...

Can my plan work?


let's try out if this work with very rudimentary tools.


First the cut, with a manual saw.


Execution 8/10. It's not perfect but it doesn't impact the functionality. Good enough.


Second, I drilled the pin hole. The Dremel is fixed to the drill press, but unfortunately, I do not have the proper chuck on the dremel. I will need to use the other drill machine. Execution 5/10. It should work. I'll do better on the next ones, once the proper chuck is arrived.

Then the idea is to grind the flat area. I'm quite sure I do not have the right tool for this...


Results
First the part was difficult to detach from the plastic as the plastic melted (not much an issue, that being said). This way to do the hole should work, but let's be clear, it's one jig, on part.

Second is the the flat area. It sucks. I was not able to make it properly with the tools I have : the bit is not the good one, and the drill press is also having some play and that means there is no way to make it proper with this tooling. Execution 1/10.


Need to print more jigs and find a better solution (having no clue about the speed to use with the tools for metal surely doesn't help)... I'm not a mecanician. Mecanician would surely, certainly, do much much better than me...

Anycase, I'm currently contemplating the idea to buy a mini drill with a proper drill press in aluminium from Arrowmax which is likely to have less play than this cheap Dremel workstation... I'm still not sure it would do the job for this specific topic...

[silvertriple]

I decided to use a file, and it worked better...


I will proceed with this approach to do a few more parts, and this will be good to go

[silvertriple]

With a simple file, it works better...



And sicne this is working, it is time to elaborate a solution for the pulley shaft.
First step is cut and file...

Then the idea is to using a saw to do the groove for the e-clip. I had an idea for this (bearing and saw not present on the picture).


A few print later...




And it's time to experiment the solutions I thought about. The groove could be a little bit more deep, but now it his in, make it deeper should be easy...



Need to cut tensionner shafts, and to as well cut the pins and fnd a solution for the suspension shafts... But al of those should be easier than what is done already...

[silvertriple]

I got the groove deeper just by applying more pressure to the saw for longer time with the same setup. It works


And yes, @Dadio, it would be probably easier to do it with a lathe, but I can't help finding inventive ways to solve problems with my 3D printers...

[silvertriple]

Only thing left to do on the differential shafts is the hole for the pin... And it is more difficult than I expected. My first attempt was without the dremel drill press because I did not have the proper collet. I used the drill trying to get it properly centered and it worked good enough...
Now, I tried with the dremel drill press and this crappy tool hass too much play, and the drill bit is shot... I succeeded to drill about half of the 4mm and it's not moving further anymore. Plus the plastic around has melted, which doesn't really help...
In short, I'm stuck here. I succeed to do one diff shaft and not more. I still need to drill 3 of them...

[silvertriple]

I still need to cross drill the differential shafts... The printed plastic hole doesn't work good enough for the centering of the cross drilling. I discuss with @Dadio, and he suggested to use a piece of rod drilled in the center section to guide the drill bit (super easy to do with a lathe, but I do not have one).

But first I needed a more precise drill press... I ordered an Arrowmax mini drill during the black friday, and it arrived promptly... But I must say that I'm a bit disappointed by the platform : the drilling bit is not centered in the hole of the platform (seems like amateurish work - this version has a piece to allow orientation at angle, and I suppose the offset linked to that part was never taken into account - I would have expected something more toroughly thought)...


Once you know it, at the end it is just question of measuring to do the proper centering... Then I built over the idea and decided to use ball bearings...




Now, I just have to find a better drill bit. The one I use currently is already dead, but at least it allowed me to confirm the centering is working as expected. I'll get proper drilling bits in 2mm and I'll expect this to be a long drilling exercise due to the limited rotation speed...

[silvertriple]

The dremel workstation is crap, the arrowmax mini drill too slow... I took a different approach considering that the proper guiding would be enough to make proper holes with just the normal drill if I pay attention to make it right... Two drill bits broken later, I have my 4 shafts for the diff.


What remains to deal for the metal parts are :
- 4 pins for the diff (2mm) - just cut, this would be easy
- 1 bevel gears axis (3mm) - just cut, this would be easy
- 8 suspension shafts - cuts and flats, this would be again an easy one to deal with

[silvertriple]

Today, I cut the last shafts I needed for the Zerda (again a template set in 3D print to set the cuts and flat areas). I intend to fix the shafts using grub screws set in the arms.


I need to work out a template to drill the arms, and once this will be done, assembly can start...

[silvertriple]

All shafts done and ready... And, yes, there was no lathe involved in any of those parts at my end : just ideas and very basic tools...

[silvertriple]

I've chosen to fix the suspension shafts with a grub screw positioned in the arms... But this require precise drilling in the arms. Nylon is easy to drill, and I have now some precision tool...
I used a printed jig to drill precisely. Beside this, I will prepare an amended version of the arms specifically designed for this...


And as we need to carefully set this on both side of the arms, and there is two different lengths, that makes two jigs.


Maybe I need to do a full inventory of the screws and nuts I need for the build now...

[silvertriple]

Yesterday, I printed the pulley cover in Translucent ABS, and I decided to try something different... I used PETG as support interface material...


The PETG was mostly removed...


To remove the last bit i used a grinding tool... It's not perfect, but much better than what the previous ones I printed...


I noticed that I messed up my order for GT2 pulley. Instead of ordering a 4mm bore for the inside pulley, I ordered a 5mm bore... But I have easy solutions : a tube, some plumbing basic tool to cut it, and a hole drilled in the right place...


and : voilà!




Then I used silicon tubing to do the required sleeves to center the pulley and rollers. It might require some adjustment, but it would be super easy to cut new ones...

[silvertriple]

Time to play with colors again... Rit Dye Orange Apricot


If ever you use this dye tone, be careful, the bubles are giving a clearer tone to the parts compared to what it is in reality... As a result it is a bit too dark compared to what I wanted initially... But it will be fine and different...

[silvertriple]

Problem of the day : king pins.


I know that my friend @Dadio would say it is easy to do with a lathe (i'm sure it is, by the way), but I do not have a lathe...
As usual i'm going to work aorund this with printed parts, a file, a few screws ball bearing and a drill. Starting point will be a 3.5mm screw. I already printed the parts, the 3.5mm diameter screws I'll use as a starting point should come tomorrow.