TOPIC:

The centering pin holes where until now guestimates based on my first try...
I did it more methodically this time...


Conclusion of the test with 4mm centering pins:
- 4.01 mm is perfect for the base : it enters but don't move
- 4.02 mm and the pin is sliding perfectly...
- anything more has more play... I could have do my uprights with more precision...

The precision is quite good and this will be used for any of the next parts...

The home fablab got slightly reorganized... This is close to my final target. One of the resin printer is still in this area but this is supposed to change at some point as it will go in the garage. It's currently not accessible, but the target is to get it installed in the garage.


The X1C and A1 Mini won't move anymore, but once the resin printer and wash station goes, I'll add some shelves for material storage...
Both Carvera Air and H2D have there definitive place. I'm targeting to install the AMS on the right of the printer. I've not bothered yet to install it correctly, as I intend to order a second AMS and 2 AMS HT to work with the H2D... 
And my wife found some room for her hobby stuff as well...

Another part made yesterday... With some fails, learning and redo better...

I needed to finish the motor pod, with the rear part... A bit of planification, and I decided that the chamfer will be done within what I think could give the best result : a pocket with a flat end milling bit. 

Therefore my work started with two supports I'll use later on...


Then I did used a 10mm aluminium stock reduced to 8mm using a pocket and a contour to get my starting point... On which I engraved a logo


Then, next step was to drill and thread the two side of the part... spoiler : I did this wrong at first, and I had to adjust the method after the second part to get it right.

First method was wrong as the part was not fixed strongly enough


Second method was wrong as the part was fixed but the 0 derived from anchor position and thickness of the material was off.


I reapply the same way for the 3rd part, and set the origin right with the manual probe. Lesson learned : when precision is required do not assume work origin postion from a derived position.

Next, I fixed the part in the defined support for the last operation and did a 2.5mm pocket where position was less important because I applied an offset to the contour of the pocket...


And here is where we are now...



At the end, CNC machining requires precision and proper planing. Clearly, trying to go too fast is not going to help : taking time to make sure the part is rightly positioned and the origin set properly is definitely the most important thing...

 

Seems you getting this down sooner or later Marc!
Hop ups is endless now.

I would like to order a custom alloy motor cover/heatsink for Hornet / Lunchbox if you go that route in the future 

As with 3D printing, I do not have any intention to make myself a second job with my hobbys Hobby should remain a hobby
 

I redesigned the front master piece to suit with CNC machining...




But designing the part is not the most complex. The most complex is really to think about how to do it... Due to the round part, it will involve 4th axis... As this is the only way I can think of to do the round part while having a 90° degree angle at the end to center it in the clamps...

This means I will have to work out about how to use 4th axis... That's where the fun begins...

Makera CAM only support relief toolpaths on 4th Axis at this stage which means we have to think about 5 steps for this part : the rounded part and the 4 faces once the rounded part is done...

First, let's try with some epoxy to understand what we have to do on 4th axis and where we have to position this.
I defined a stock in Makera Cam and a cylinder with the expected diameter and expected length. Looking at tool path, I had a doubt on the way it was handled... 


I set the 4th axis, an epoxy stock and let's go.

With a step down of 1mm, Epoxy is quick to cut...


Quick learnings :
- diameter is not exactly as expected. Rotation Z-offset may need some massaging (well, I should have done in Aluminium first before doing this).
- roughing and finishing pass can't be done is one single gcode: Rotation axis A value keep increasing, and once the first tool path is done, it would take about the same time to get it back to A=0 to do next tool path. Rather go for 2 separate gcodes and shrink A value to reset it into 0-360 range before starting second gcode
- tool path calculation doesn't account for milling bit diameter during a relief path code : which means that if you need the cylinder to be 54.2mm, you have to remove the diameter of your milling bit from that value
- work origin by default doesn't take into account the chuck size, you have to include an offset to take this into account (about 30mm) so it position the cylinder where it needs to be...
- I measured some deviation from what I expected along the diameter with the higher value on the chuck side and lower value on the tailstock side (about 0.15mm with epoxy)...

Taking all of this into account, it is time to work out an aluminium part...




New learnings :
- deviation is lower than with epoxy with the alumium part with around 0.05mm deviation. This maybe because Epoxy is more flexible and that step down with epoxy is higher (1mm instead of 0.2mm).
- my round cylinder is too small by 0.30 mm. I can easily address this by sanding the bottom of the top clamp, so I'm not sure I'll redo the part if I don't do more mistakes... But lesson learned : rotation Z-offset should not be modified based on a flexible material. I restored the initial value
- It's visible on the round part it was not done on a lathe, but it is functionally workable to do round part, although it may need some sanding for a nicer finish...

Looking forward for the second part of the headache : properly positionning the part for the next steps which handles the 4 faces work... Main challenge is to understand where the center of this part is.

Once the cylinder was done properly, it was time to get to the rest of the part... Which means basically 4 faces, and something to do to remove any uncertainty in the centering of the part...
The pocket of the Manual XYZ probe is not usable in every single context : if the part is not high enough, it doesn't work. If the part is too small it doesn't work. If you want to locate 2 different point to find a center it doesn't work either... What we really need is to be able to locate the edges of the cylnder or the square area...

The bed of the Carvera is isolated (as long as there is no centering pins to make the contact between the bed support and the part), so I decided to use a  small device with a led, to replace the led by a red led, some wires and crocodile clamps... One clamp on a fixation, the other on the tool, and the led lights up once we get the tool in contact with the part. This is simple. And it worked.


I identified the location of each edges I needed to find the center of the part, and I set my offset accordingly...


That allowed me to drill centering holes  and fixation holes. With the idea I would use the same holes in a defined position on a piece of stock to set my work...



It would have been perfect if my part was totally flat on the bed when I drilled the first holes in the part... I noticed it right away, but decided to proceed until the end to find out more issues so I don't make mistakes next time.

Logo engraving


Then pockets


First face done, mainly with pockets and contour, and a chamfer to finis the part...


Next was to turn the part and operate the same operations wihout engraving... But as the centering holes were not perpendicular, it was wrong... I also figured out another mistake while doing the bottom and top faces of my part, where the stock I used to fix the part was actually slightly bigger than announced (no pictures, but that mean you don't have a hole centered)


I redid the part (it takes quite a while, about 2 hours to get the 4th axis done, about 1 hour and a half per faces, and time to do the fixations, configuration and center location). It was obviously better this time...




Then with a proper location of my work origin and the proper offset, it was easy to pull the last steps... I repeated the same operation for each bottom and top face, including work origin setup...



And we finally have a valid part...




And it goes nicely on the chassis...


As the tranmission is targeted to be printed on this car, what remain in terms of work is the servo supports, and the battery fixation system (which will be different than what we have for ST-1)...

I have the Carvera Air for a bit longer than a month now.

The ST-1 SP is completed for the CNC part... Transmission and carriers will be printed, and at the end what remain is assembly...




For me it is time to do a small return of experience on the Carvera Air... 

First let me precise something : I was a complete beginner when I ordered the machine, and this is important. I'm impress by what I've done since I have the machine. Some of my friend more experienced in CNC are telling me they are impressed by my result in so short time frame. Some of my parts are not perfect... But with the little bit of experience I gained, I could eventually redo them better...
All come to one point : Makera made everything possible to ease the life of the beginners. 
- They provide a tool set library with material presets that allows to have a good working starting point without any problems (and this toolset library is available for most of the CAM software). When using Makera Cam, once you set the stock, when you choose a tool path and tool, it comes prefilled with the default settings for that material. You just have to think about what you want to do at the end, and that certainly makes the things easier...
- The provided gcode examples are easy to use and really show how to use the machine. That is also making it very easy to work with, as you have within the example a few elements to show you how it will work once you prepared a gcode. And their Youtube tutorials are also helping when you have a doubt.
- The machine accuracy is perfect for me (way more than what I was expecting). Most of the accuracy problem will come not from the machine but from the way you fix your stock

In short, the Carvera Air is a very good machine, and I do not regret buying it. I would even redo it if I have to reset my choice now.

That said, they could improve a few things :
- a more polyvalent edge finder. The proposed solution only works to find the top front left edge of a stock high and large enough (more than 10mm and 5mm large), and it doesn't allow to find edges inside a part. I workarounded this easily with a led, battery, wires and some crocodile clamp, but I wish Makera could improve this easily with a better option
- there is part of the Makera fixations that did not come with the Carvera Air. Those are the Thick L anchor and the Side clamp set. Some of the reviewers got them, but it was not in the pack with commercial machines. That's not too much a problem, but should be announced right away
- they should propose a low profile vice to set on the bed and being able to work with one or the two anchor positions
- they should propose a vice working with the 4th axis
- Makera Cam should include more functionalities for the 4th axis : at this stage only relief is supported, and it would be great if it was possible to do 4 faces parts without detaching the part from the 4th axis. Some CAM software allow this, but they are all paid software. I may consider DeskProto for this...

At the end, I love this machine, and it will be of use in many of my future projects...

Really impressive result. Congrats.

I was not very active on the forums those last days... My brother was at home, and he was very curious about the Carvera Air. He have a CNC (Sainsmart Genmitsu 3040) and he went with some ideas where I could help him to work out a small tool, that could be usefull as well for the Carvera Air...

One of my key reproaches to the Carvera Air is indeed its probing hability... And my brother's project was basically to build a 3 axis probe, based on gravity, with 3 ball bearing balls, a dremel shaft, a PCB and some copper wire, and some printed parts...

We did iterate the elements a bit over 3 days of work...

The design...





The way it works is that it works on contact loss... We used the XYZ pocket probe and the wires to work out contacts with some crocodile clamps as I did not have jst 2.54 xh 4 pins connector at hand... You may note the letters (in the wrong direction as I addec them late last night, and I did not want to reprint the part again) over the 3 screws using to set the inclination of the probe shaft...



Playing with the screws I was able to obtain an almost perfect lining of the probe shaft, and the measure on repair A, B and C were the following, and they were repeatable, which somehow shows that it brings a bit of precision...


At this stage, I may now consider the community firmware and the community controller which are adding quite a few possibilities in terms of probing to the original Makera firmware, and this may allow to work more easily for parts requiring centering...