New CNC Router

[phillby]

Hello everyone,
I have nearly finished building The Jgro Router Mechanicals, a big thanks to Jgro many are indebted to you for the excellent plans. I have not been posting anything on the mechanicals as many have been there before me. However I would like to share my experiences on the Electronics. I and many others will be very greatful to Pminmo a member of CNC Zone.

http://pminmo.com/

First a few notes and maybe a question on the Mechanicals.

In Oz we have the pleasure ( or something ) of working in both Metric and Imperial. So when I choose the lead screws I used 8mm 1.25 mm pitch. The angle is similar to UNC at 60 degrees.

However all the 1/4" bolts and setscrews are BSW which has an angle of 57 degrees. Some of the tapped threads in the MDF stripped, I eventually prevented this using sanding sealer ( a very thin varnish type substance) which I used in every hole after it was threaded. I could have used CA Glue (superglue) but it is less forgiving to fingers and the like. All the # setscrews were replaced with 5mm ones. These changes were made because the original specified ones are hard to obtain. ( read expensive).

I do not have any machine shop capabilities so evey thing was cut on a tablesaw and the Dados (or rebates) were cut on a router table. Holes were drilled on a drillpress and most threads were taped using a cordless drill.

I drilled as accurately as i could mark using one piece as a template for it's twin and using each piece to position the drill for its mating surface. All this fitting was done using a pilot drill of 1/16 of an inch. I used another 1/16 drill or two to hold the piece in position while second and subsequent holes were drilled.

I did not use clearance holes on any pieces if a hole had a 1/4 bolt I drilled a 1/4" Hole.

Now my question I drilled 1/16 pilot holes for the dowell pins but have not used any as yet. My question is " what are the advantages of the dowell pins?", as I did not use accurate maching (i.e. CNC) and did not drill clearance holes. I could drill them now while assembled and this could provide more strength or not use them at all if. If some parts need more strength would it not be better to use another bolt?

Just a note the Z-Axis MDF liner bearing carrier is a different width dimension in the materials list to that shown on the detail drawing. I used the dimension in the Materials list. It works by using 3/4" long setscrews in the adjustment blocks instead of 1".

I think I have waffeled on long enough I will discuss electronics in another Post.

Brian the sawdust maker.

[phillby]

Hi Again,

While deciding to build the CNC Router I decided to build my own electronics. I should be capable and this should save money the oniy way I can afford this project is to keep the cost to an absolute minium.

Early research suggested Unipolar was simpler as it was mostly discrete components. Seems easier than those multi-legged things especially the tiny ones with my eyes.

After a false start through insufficient research and purchasing too small stepper motors I was offered some 116 oz/in (may be from a HP Printer) Steppers. On decyphering the specs I find that the torque is

116 in Parallel Bi-polar
116 in Series Bi-polar
82 in Unipolar

There goes the Unipolar. Ok but 2.5 A is on the high side for many designs
so lets go series only half the current. But you don't get any thing for nuthing.
higher speed torque drops of quicker with a series connection. Jee I've disseminated a lot of information in six weeks since I started building this THING ( I doo luve it really ).

Ok, we have decided Parallel Bi-polar and Phil (pmino), see the first post, has many great designs. So here we go with the Allegro A3977SED single sided board. I was going to use the Opto Isolated Breakout Board but cannot find a supplier for the Opto-couplers in Oz (too hard to get them from overseas) Phil, Mouser only lists an equivalent.(Thanks). I will use the standard 4 axis BOB and use only three.

Next post I will describe again my method of toner transfer as I would like it to appear in this Build-Log.

Brian,
The Sawdust Creator.

[phillby]

Hello again.
It took great courage to start the Laser Transfer process, of course it is difficult to source Staples paper in OZ so tried what I had. After a couple of false starts with other paper, I used Artwrite / Pelican High Gloss Everyday Photo Paper. The interesting thing is it seems to be plastic and has a transfer layer which goes sticky when water drops go on it, even when used for photos. It seems to do an excellent job better than the Blue paper produced for the original Toner Transfer which was hellishly expensive and needs a very dark thick toner layer.

There was a really good glossy toner layer left with very few places to patch up.

More on the paper the Packet has a diagram which shows 5 layers
1. The transfer layer
2. The Absorption Layer
3. The Primer
4. The Substrate
5. The Antistatic Layer.
My daughter purchased the paper 100 sheets of A4 (10"x8") for I think about $AUS 18.00 at the supermarket for her photos, I supplied the money.

The images were printed using a HP Laserjet 4050N. To iron on the image I used plain copier paper between the photo paper and the iron to prevent the plastic finish from sticking to the hot Iron. The plain paper stuck to the back of the photo paper. Beware SWMBO will not be amused if you ruin her iron.

After ironing with a lot of pressure using all sorts of technicques the flat, the tip and the edge of the iron for 3 - 5 mins., the plain paper even discoloured from scorching a little, it was of to the tap and a bowl of water. My iron was way too hot on max heat. The scorching happened even at a lower setting, maybe I could even lower the heat level some more.

After about five mins I started to peel the paper very carefully of the copper say a few millimeters (1/8 inch) at a time before soaking again for a few mins then doing a bit more until finished. Leaving the board and paper in water overnight did not make it any easier to peel of the paper (plastic). Never the less the results were still good.

A grey image was left like a very faint shadow on the paper just like the toner discoloured the sticky top layer of the paper, if there are any black specks then that part needs a toner repair (sharpie permanent marker).

I have completed two boards using this paper and technique and am very happy.

I relate all this hoping others may find similar paper and have the same success I seem to be having.

Brian
The Sawdust Creator

[phillby]

Hi everyone,

Well I have completed the 4 axis BOB Board and tested it. Pics have been taken. I have nearly completed one of the Single Sided 3977 Boards & have been inspecting the soldering with a magnifing glass and multimeter very reguarly (my eyes are no longer as they used to be.

Question: I have read the warnings about not disconnecting the stepper motor while the Power is on, But can you test the board without the motor connected?

As I have only the final stage of testing to go before soldering in the 3977 (I am dreading the even thought of that) I really need an answer to this one. I only have 3 chips and don't know if I can obtain any more, so am being very careful.

Thanks in advance.

Brian

The Sawdust Creator.

[randyf1965]

Yes, I used 2 led's connect anode to cathode with a 1k current limiting resistor per winding . so I had 1 set across a1-a2 and 1 set on b1-b2 when the stepper turns the light flash on and off according to the voltage being applied.... pretty cool the first time you step using a new board.

[phillby]

Randy,

Thanks. Why 2 leds in series is that to get 1.4 Volts drop?

Let me draw in text what I think you are suggesting

Output -led+ -led+ 1KR Output

This then is connected to each pair of outputs. Which is the more positive Output 1A or 1B I assume 2A & 2B re in the same order. Sorry I am really careful. I have enough accidents which I dont think enough about so the ones I do I try to check first.

Did you limit the current on the board as well as the 1K resistor. I will be eventually setting the current limit to 2.5A as that is the rating of my Steppers. Initally when finished with testing I will set lower than this ( just to be cautious), say 1.5 A using the trimpot.

What software did you use I haven't really decided. I have the demo versions of Kellycam, Mach 2, and TurboCNC.

Unfortunately (maybe) the PC I have aquired for CNC has XP already installed not easy to remove. I have no running verions of any thing else to make a boot disk. Has anyone used Freedos to run TurboCNC?

Thanks Again

Brian

[randyf1965]

Here is the link for the light circuit:
Let's Get The Show On The Road......

and 10bulls image from post #405 in that thread

I have used turboCNC (too old looking ) and Mach2

[phillby]

Hi Guys,

I have been in direct contact with Phil and will sumarise so that all can have the answers. Here is his reply.

Yes it can be powered up with no motor connected. I in fact would recommend that. Do some ititial testing to make sure you have power where you should, set the current... I assume your building the single sided 3977, which version? Keep me posted on your progress, I'm always interested in each users comments. Some it goes smoothly, others not so smooth. So far I've been able to work through them all. I've been contemplating getting a batch of a smaller version of the 4 axis board and either the single sided or double sided 3977 boards made for people to buy if they want. I've not personally made the single sided board, but I may be able to get them cheap enough to sell for $6 or $7 drilled, solder mask, silk screened as well as the 4 axis board. What are your thoughts?

I then replied.

I am making the single sided board version A but removed the drill target around each hole. This to me just makes less copper. I think there is a mistake on the SS board and circuit diagram, there is no pull-up on pin 1 of the 74HC14. I noticed this when the instructions asked for checking 5V at pin 1 with it powered up and the chip in. there is 0V at this point so pins 2 & 3 are High 4.98V. I compared the circuit of the double sided board to come to this conclusion.

Which he answered

As far as the single sided not having the pullup on pin 1. It's not really a design or usage issue, although in downsizing the single sided to see about a commercial board I added it back in. It will work just fine with or without, just that I need to change the single sided document.

Yea the .2 ohms are pricey in a precision resistor, I've moved to a surface mount part that is a third the cost, and in the 2 watt package it's large enough it's not bad to solder. Second picture down, the two blue surface mounted parts with R200 on them
http://pminmo.com/gallery/2.jpg

Once again I thank Phil for his patience and help to all who ask.

I will get those Pics on tonight.

Brian.

The Sawdust Creator.

[phillby]

Ok here are some pictures. I am elated at my achievements but not with the pictures.

1. The peeled off (plasticy) paper from the toner transfer of the Bob Board
2. The Bob Board.
3. The Driver Board.
4. Jgro's Router
5. The Router Bridge

As I said not great pictures.

Brian

The Sawdust Creator.

[pminmo]

Looks great, keep us posted.

Phil

[phillby]

Ok Guys,

I am about to put power on the 3977. I hope the smoke dosn't escape. I have done all checks I believe possible.

Just so I get this right for testing.
1. I have put two Jumpers on the step mode to give full step.
2. I have put a jumper on the enable Input.
3. I have put a Jumper on the direction select. ie hardware reversal points.
4. I have connected up the diodes as shown above. Post 7, Thanks Randy.

I think all that is now needed is power and step signal.

Questions:
1: Will a nine volt battery provide sufficient current for the circuit and leds?
2: will I see a single step on the leds (i.e. manual ground on the step pin)?

Thanks in advance

[pminmo]

9V battery will be close, but should work. More the voltage than current requirements.

Phil