My uninerversal vitamin The Nylon Corner Block

Seeing all the Rep Strap Mendels appearing in many forms. I thought it was time that I made use of My universal Vitamin the ever faithfull Nylon Corner Block ( Fixing Block, Fixit Blocks, Assembly Joint) as I am a very lazy builder of RepStrap machines not completely unskilled as a carpenter or metal worker and one who likes the whole concept of KISS.

For those who don't live by KISS it is the Acronym for Keep It Simple Stupid I like this principal and that of spending as little as possible to achive my goal. Also currently being without income is another contibuting factor to this need.

So from watching and pausing the excelent overview Videos then examining the drawings and pictures made by triffid.hunter and : swighton I have been able to build my low cost low tech version of Mendel using a few  Nylon Corner Blocks I will attempt to build the Mendel frame from scratch in a day/weekend here goes. a pictorial build. Start time Saturday 12 December 8:30am.

From Blogger Pictures

From Blogger Pictures

 






The Esential Build tool for making any kind of Repstrap with Nylon Corner Blocks a build Gauge so all bars are Eactly the same size Ideal for Kebab Quality control.




In use.. Making the plain side bar Two required.




Making the motherboard and extruder mounting side bar 2 required.





 Making the bottom bar with Stepper controller mounting board 2 Required Note both pairs with extra Nylon Corner Block made as mirror images of each other.




All the Kebabs made Time for a quick Coffee Break and two slices of Toast.. The I will see if the Sides are Equilateral when mounted on the blocks.

Wey Hey it worked.. well it looks  Equal onlt time will tell thou.



Out of focus sorry Detail of the Nylon Corner Block mounting using one wood screw to hold it together.



Now to make the other side.. Oh mistake no 1 above I did not use the Mother board side bar it became obvios as I had two for the next Mendel side.. Opps.



And two together..



Next to put the two together... off to read the Mendel assembly guide... not sure which is the next bar to use..

Hmm Slight change to Mendel design  Nylon Corner Block Mendel Needs Legs Have used White Nylon Blocks to make the Legs stand out I have also made Nylon Block type 3 wich has an 8mm hole for the slider bar and one of the two holes drilled out to 8.5mm.



Build so Far Sarurday 16:42 build time 7.92 hours Tea break time as Midge is back from Art Class.



Time to make some more wooden bits for the slider rails for the Z axis as the bars are no diffrent from the corner blocks I will make two more corner blocks and fit the forth type of Nylon corner block this will have a the single hole drilled out to an 8mm hole to grip the Z slider rods and will be screwed to these two new wood bits.

The build will not fitt in the photo booth now! It also needs to be squared up as it has a 2mm wobble the same as a Darwin needs Squaring up the wobble on Mendel seems less than the two Darwins I built so its looking good.



Basic assemble of the frame completed now I just need to add the X and the Y Axiss to finish..

Jobs to do Make X carridge assembly Make motor mounts for Z and X and sliders. Make Stepper controller mounting board Make motherboard-Extruder controller mounting board. Make build platform board.

Saturdat 17.49 Build time almost nine hours and a break for Merlin.

Made the following PCB mounting boards and drilled the 8 4mm holes in each to suit the Nylon corner blocks. Layed out the PCBs and drilled the other holes to mount the PCBs.

Motherboard mounting board 290mm X 98mm x 6mm
Stepper mounting board 380mm X 80mm x 6mm



Made the other thick pannel boards
Print base board 230mm X 200mm x 6mm



Z slider mounting pieces.





Midnight Saturday 11 hours spent on the Mendel build End of Day one.

Bertha cuts her own T slot work clamping base

Using the Dremel Key hole router bit 655 not quite its intended use but it works well once I figured out that 10mm a min was the best speed for a 7mm deep cut and almost the slowest speed on the look alike avoided MDF burning smell. so it takes 30Min's per slot to cut there are 19 slots ie every 20mm. I also learn a little G code in the process.



The process has identified that I forgot to put the collar back on the X axis drive shaft when I added the two extra runner on the X axis. Oops so there was a 2mm difference between the start point of the first X T slot to the start of the last X T slot. As the Slots are only for Clamping stuff down is no big problem tho.



The bigger problems are:-

Finding a reliable way to set spindle speed on the look alike.

Finding a way to stop the filters blocking on the hover when cutting MDF.

Modifications required:

Fit the Collar on the X axis.

Upgrade Y and Z Axis's to have motor couplers, bearings and collars like X instead of Plastic tube and tie wraps... Coupling... Thou neither the Y or Z axis had any measurable error like the X had.. the solution for X is more mechanically stable thou..

An electronic switch to turn the spindle on and off.

An electronic switch to turn the hover on and off.

Maybe make some kind of spindle speed detector to have complete control of spindle speed.

A busy weekend in Gloucester making a Double door frame and fitting new hard wood doors to my Mom's house. So not much rep rapping or CNC~ing etc.. Any way here is a quick up date on Bertha and Big Bertha the projects.. Some brief details on the Big Bertha project blog. Slightly earlier than anticipated due to the success of Bertha.




Also last weekend I added the 2 extra runners on the X and Y axis of Bertha.




Bertha completed over 110,000 lines of G code using the pic to G code function of EMC2 I made the mistake of clicking on invert image so I stopped the G code some 120,000 lines early. lessons learnt dont make the first real job for your CNC a big one a 9.4 MB Gcode file is > 200,000 lines of Gcode set the feed rate higher than 120mm a min and a cut of depth 0.1mm.

So the carve a logo exercise ended up as one long soak test.
Great result though Bertha did not fall apart it did not lose position and the low cost look like a Dremel did not fail. Other lessons learnt you need a fan for the X Axis motor or run it at < 2A. An aborted Bodge It Logo around 100mm x 73 mm~ 3-4mm deep. Note the invert function takes the regular G code and reverses the code order not a good idea as it re cuts seach layer.


Oh and not forgetting the picture of the Wind and Solar powered speed caution signs seen on roads around Gloucester.

Y Rod mount amd Y motor mount

Click here for Full details of Y Rod mount Y motor mount

Pictures of the rebuilt Bertha now as a CNC

A work in progreess with axis transion speeds of > 30mm /s

I'm working on making the as yet unsupported trapezoidal spindle drive shaft to make it so that its supported with bearings, this will allow a much higher axis transition speed. I'm also will be improving the rigidity of the Y axis by adding two more 8mm y Axis slide bars the beauty of using the nylon blocks as the mounting method has saved around £70 the cost of a traditional CNC slide system.



Here is a picture of the first test routing performed.. using a cone shaped dremel bit no 125



I am still having intermitent problems with the Z Axis home opto sensor despite ex-changing the sensor for another one and changing the parallel printer port input pin from 12 to 13, using USB double screend cable and adding high and low value capacitanc to the 5v supply pins on the Opto sensor PCB.
I have also reduced the length of the sensor cable run that is spiro wraped with the stepper and dremel power cables. curently run out of ideas to solve the problem.
Correction its a Dremel look alike from Aldi.. I do have a puka Dremel as well as several other imitations. I also have a giant 700W dremel type tool from the B&Q P Pro range this will be used on Big Bertha .. Yes a 700w with a small collete pin chuck just like a dremel.

More pictures of Bertha and its insides on the BodgeITQuickTools blog.

Ps Midge just asked why I didnt sand the test piece to make it look better. It is as it is off of Bertha.. I didnt use a small dremel 105 engraving bit as I did not know if Bertha would work hence it is a rough cut in the beach ply that is 0.02mm deep (If my stepper configuration settings are correct ) I dont know the speed of the cutting either but it was finished /done in less than 2 min.

X and Y axis sliders method 3 ONLY for belt or ball chain drive.

I am total amazed by this one I expected this to have more friction than the skate bearings and for it to have a lot of play.. neither is the case it is also very very much lighter as it has not got 32 skate bearings. I cant belive how simple the X & Y mechanisims are now and its £16 cheaper to buy..

X & Y Sliders method 2 is for using Bike chain

After testing method 3 with Bike chain I have found that you must use this method.
Its a bit of a catch 22 ~ toothed belt rus great with method 3 and is closest to a printed Darwin.
However with bike chain the extra weight causes too much friction and skate bearings are needed. Skate bearings and bike chain are cheaper but in the long run you will need to buy toothed belt. I will continue to look for an inexpensive reliable method of making ball chaine drive pulles as this solves the catch 22 by eliminating toothed belt.

X and Y axis sliders method 2 tyring to avoid drilling big holes in wood and keeping it simple to make. Making the sliders out of Nylon corner fixing blocks.


Here are the full details of the construction. X & Y Sliders method 2

Follow the link to Repstrap Dawin for

> Making 20 Diagonal tie brackets & 4 anti vibration feet <