Constructing the Mendel parts out of MDF (Part III)

(1)

Well, at this time i didn't have time to continue milling the parts of reprap. But i said in previous post i'll show you some of the tools i used to shape the parts.

At first i have to say that a rotary tool, which is a tool that speeds too fast (maximum 35.000 rpm) is a vital one.

disk for wood (2)

• With this rotary tool and a disk specially for wood (photo 2) i cut the parts.

special drill bits (3)

• For the inside shapes (circles especially) i used a bit that it's similar to common drill bits, but cuts the wood horizontally except from vertically (photo 3). 

bit for details (4)

• Then, with a sharp bit i did the details (photo 4).

sander (5)

• And with the sander smooth the edges (photo 5).

Also the holes made with a common drill, because the rotary one can hold only 3-4mm bits. Just make sure the holes are perfectly placed.


For example, the part shown at first picture made like this:

1. Cut the part from the rest of the MDF sheet.
2. Draw the layout of the part.
3. Mark the center of the holes.
4. Get the holes done.
5. Use the special drill bits for the inner circle and the biggest part of the 3 rectangular shapes.
6. Do the details with the other bit (4)
7. Use a rasp to smooth the inner circle and rectangular shapes.
8. Use sander for the rest.

The process is similar for most of the parts. But  it's better for some parts to mill them while not cut from the MDF sheet.

Constructing the Mendel parts out of MDF (Part II)

Step 2: Drawing the parts on the MDF.

drawing on the way (1)

Drawing the parts isn't something tough, but you have to be patient and careful for a good result.
At the left photo you can see almost everything you will need.

Notice: Remember what i had mentioned previously, that the outline isn't so important as the innner dimensions are.



Define a reference point to start drawing on the wood. The best is one machine-cut side because you know it's a straight line.
Get the paper and place it in line with the end of MDF or the ruler (photo 2).

placing the paper part (2)

  


At the photo you can see that i used the ruler in order to be sure that the paper is placed correctly. In other cases you use a combination of rulers to get the paper where you want it. Here you will need the corner ruler because it makes your life easier.

Drawing many parts (3)

Drawing many parts (4)

Using the rulers to draw many parts on MDF and not drawing and cutting one by one. The space needed between parts is about 5mm to be sure you'll not mess them up.

2 consecutive parts (5)

This is how the job is done. Draw a big area with parts and then start cutting. Also don't draw one piece of everything, but better draw all the replicas of one and then go for the next.

Notice: Better remove the wood from the inside of the parts before you split them because it will be difficult to hold them tight while milling them.

I can't remember something else from this procedure. If you miss anything feel free to contact me.
Next post will be about the milling and the tools i used.

Constructing the Mendel parts out of MDF (Part I)

Continuing from the previous post, the reason i chose this method was the lack of money and the tools i already had on my garage. I assume you have downloaded Inkscape and the .svg files, so I'll start...

Step 1: Printing the .svg files (Inkscape tutorial)

     In order to print the parts you must first select the area which you will print so press File->Document Properties(or Ctrl+Shift+D) and then select in the Page tab, in the Format field the option A4. Also select the desired measurement system you do want in the up right corner (General). Now you can see the area which will be printed. Just move the file and place the parts you want inside the area.

You can see the parts in 1:1 scale by selecting View-> Zoom-> Zoom 1:1.

The axis top and left are in the measurement system you picked before. Click on them and drag the mouse in the drawings so that the lines will appear.
On the bottom of the window you can see the coordinates of the line while you have it selected. On the top toolbox you can see the coordinates of selected object.

Selecting the size (3)

Moving the print area (4)

 Now you just print all the parts in paper, and start cutting with a scissors or a razor. You have to cut only one blueprint from every part.

cutting the inner shapes (5)

Notice: You can remove the paper from the inner holes with a razor at this moment and transfer it to wood or you can first cut the outline of the parts and then finish them.
Take care that you have to be very careful with the distances from hole to hole etc, rather than the exact shape of the part for the majority of them.

Constructing the Mendel parts out of MDF (Intro)

In order to save some money i'm trying to make the parts of Mendel out of MDF (wood). The construction is still in progress, which means i can't tell you for sure that this idea will work. I used the files for laser-cutting from http://reprap.org/wiki/LaserCut_Mendel#Downloads. Download the .svg files and use the Inkscape to open them. This files are used to drive a laser cutter, which will produce easily the parts. If you don't have, then you will need patience and enough tools to shape them.
The process in short is:

• Print the files in the original size
• Cut each piece
• Draw each piece on the MDF
• Cut it, not with much details
• At last edit each part in order to reach the desired detail.

Not very easy as you can see, but if you got already the tools the cost is 10-20 euros! You can save 150-200E. The process goes on...I'll come back with more details in a few days, presenting an almost step by step guide.

 Some photos to get an idea :) 

                                                                                                       

Making RAMPS v1.2 (Part II)

We have created our board and it's time to solder the parts on it. I started soldering the pin headers, because they create "blocks" on the board and i could easier point out where to pick the other components.

large pin headers (1)

 First of all solder the pololu's pin headers. I soldered the Arduino's ones (photo n.4 ) but this wasn't so good in the end that i had to solder top wires and some components near those pins. On the second photo (2) you can see that more pin headers, the smaller ones are soldered on the board. It doesn't matter if you solder pins or resistances for example first.

smaller pin headers (2)

 Notice: You must have in mind the next things you are about to solder on the board in the "neighborhood". In order to have some extra space for your own convenience.

snapshot (3)

Above, snapshot while i go on soldering. It's not so hard, but i am not the perfect as you can see in the bootom of the PCB. The pcb at this stage is finished with the small parts. Just missing the screw terminals for the motots and the Arduino's pin headers.

Arduino's pin headers are a bit tricky because we have one layer pcb, which means we have to solder them from the same side which the copper is. Check put at next photo. The reason i soldered those pins first, was to check that the PCB "locks" on the Arduino. I was anxious about it :)

Arduino's pins (4)

Notice: You can check this "lock" without soldering. Pick the pins, the male ones and put them into Arduino. Then take the PCB and put it above. It may not fit well but the headers are not also soldered. If it seems to be very tough then re-mill the PCB. I got something like that without pushing to the end the PCB. 

PCB and Arduino (5)

top wires (6)

After finishing with the bottom side, check at this file the extra top wires. They are noted in red color and are about 10 to 11. You will need to be delicate, otherwise solder them, while you are soldering the others parts.

almost ended RAMPS v1.2 (7)

An almost finished RAMPS v1.2 board, I'm still waiting the pololu drives and waiting to see if i will put the diode.

The biggest part of the job has been if reach at this point. But the greatest thing is to test it :)

Also NOTICE: Check for short-circuits!!!!!
You can check at the end, or after finishing a block of parts. Don't forget it!



P.S. Feel free to comment and ask for extra descriptions i may have omitted.

the lab :)

Making RAMPS v1.2 (Part I)

I started to thinking about making a reprap machine time ago. When i had bought the needed things for RAMPS v1.2 i noticed that v1.3 and then v1.4 showed up. But it was already late. So at first i will try to explain the process i followed to make the RAMPS v1.2 board.

ramps v1.2 board (1)

     Notice: If you follow this guide will have to make your own board. I will explain the process in another post with more details.

Step 1: Obtain the files :)
     from the wiki: http://reprap.org/wiki/RAMPS_1.2  as you can see there are instructions, but some things were not so clear and the whole process is used in other cases as well. So you got the right files from here. They are not visible any more on the wiki.

Step 2: Print the .pdf file in transparent sheets, better two of them. Cut them and place one on another, then use some tape (see photo 1). Now your ready to use the dark room :)

box for pcbs (2)

Step 3: You have bought some pcb already i suppose. I used a photosensitive one. So now it's time to transfer the circuit to the board. I used a box like the one in photo. Cut the pcb in the size of the circuit and then remove the protective sticker. Now place the board, above place the transparent sheets with the circuit and then as you see i put a piece of glass in order to hold them firmly (photo 3). Close the door and light up. I can't tell you exactly how much time you will need. I left it for 10-15min for sure.
     Notice: It is better for your board to be in a dark place in the mean time that your board doesn't have the sticker neither the sheets on it. A little light just to see what your doing.

order of sheets (3)

     Notice 2: After the transfer, you must have the developing mix ready.







Step 4: Developing. Now the light from the bulb has burnt the board's protective photosensitive layer except the spots under the black ink. The copper is now almost uncovered. We need to remove the rest of this layer using Sodium Hydroxide (NaOH), also known as lye and caustic soda. We will need a half a spoon. Put the soda inside a wide bowl and fill water 2-3 fingers high. Make sure there are no solid soda and then drop in the board. You will notice a black-to-pink colored layer being removed from the board similar to the one printed on the sheets. Remove the board from the bowl and wash it with water. If you still see some layer rub it gently.
     Notice: Use gloves for these solutions.

evaporated solutions: down:soda, up:H2O2 (4)

Step 5: Etching. The copper we want to remove is now totally uncovered. Let's prepare the solution for etching. I prefer Hydrogen peroxide (H₂O₂) and Hydrochloric acid (HCl). HCl can be found at supermarkets, at least here they still sell it. H₂O₂ is used from pharmacists. Get a clean bowl, wear your gloves and make a solution of about 1 part H₂O₂ 2 (or more)parts of HCl. Now watch how beautifully the chemistry works removing the unwanted copper and showing the circuit! The amount of HCl is used affects the time you will need but too much may remove or hurt the paths. Also the solution must  cover the board.Again wash the board and you should have something like this (except the holes):

finished board (5)

Notice: I put the board again in the developing solution (step 4) in order to remove the rest of the photosensitive layer and check for short-circuits easier.
Notice 2: Check for short-circuits!!!!!!!!!!!!!!!!!!


Step 6: Milling. The board is almost ready, we have only to make the holes. Find a base and use a rotary tool. The holes and the bits are too small to fit on a typical drill. Find an adapter or as i said get a rotary tool, which is very useful in general. The photo above shows a finished RAMPS v1.2 board ready for soldering.


Next post will be about soldering...

This blog is dedicated to the RepRap machine i'm trying to make and to the future things reprap will make for me :) I will begin with the electronics in the next post.