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Steps of DIY PCB Making

As I said in the previous post I needed to remake my CNC controller boards. Here’s the work done.

Board cutting.

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Filing.

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Edge lapping. Wet sandpaper gives great finish to the edges, and makes deburring easier.

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Cleaning. I used to use abrasive sponge here, but a good polishing a cleaning works well.

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Preparing transfer. In the past I’ve used plain laser printing method, but press’n peel paper makes it easier. I suspect scale of the Y axis of my printings it’s a very little shrink, so I will do some tests next time.

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Iron. Not too little, not too much pressure. You can guess what I did with the cloth.

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Retouch. There’s always some details to retouch; I never get a perfect transfer (please note thin lines are 0.016 width, tough). I had to repeat one defective transfer.

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Etching. Ready within minutes if you swing the plate.

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Toner cleaning. Some acetone damp papers will do the work.

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Tin coating. So great product!. Next time I will use a plastic food box so I can store it for next use.

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Checking and correcting. Sometimes there are very thiner bridges between paths. They can mess all the work.

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Drilling. I have a mini drill press, but hand drilling works far best for me. I broke several of these carbide drills at the beginning some years ago, but not this time (very frustrating, as I remember). As widely known by EAGLE users, one of the keys is to use the “limit drill diameter” ULP.

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Flux coating. Mine dry very fast, so I should apply within 5 seconds or so to get a clean coating.

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Look finished pcbs. Good enough for me.

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Soldering. I like to use 0.5mm solder wire, but this time I did all with 1mm solder wire. It’s easy to put too much solder with this.

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Mounting. Here’s the finished core of the controller.

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That’s all. BTW, at least two of these boards works well (haven’t tested the others).

Finishing my CNC controller

Ok, I know I said I would start this several months ago. But the fact is that I’m beginning just now… and the first task I need to accomplish is to finish my long-delayed cnc controller.

controller-01

I build this thing around three years ago. The chassis (11″x9″x3″) was a from an old optical reader; I love it, it’s very high quality (it’s nice to bring new life to scratch). The motor drive was the STK672-050, a Sanyo 3.0 Amp unipolar stepper drive. I did use 6 pin mic connectors, they are pretty cool. I got the 5 volt supply from a cell phone charger. Currently It’s a 3 axis controller, but there’s room for another axis if needed.

controller-02

Please note I’m aware that bipolar driving are the preferred choice for cnc equipment, but I’m confident this will do the work. Supposedly one advantage of unipolar over bipolar driving is better torque at higher speeds (look here). My choice was driven mainly by availability of this driver years ago. Now chinese TB6560AHQ red boards seems to be a better option (after reading this, I realize first generation boards where a pain in the ass); in fact, I plan to order one of these for backup and/or testing.

controller-03

This controller works very well (fast movement, not strange* noises, hard to burn), but I need to remake the pcbs due to a positional error, and after that, I need to mount the heatsinks and finish some details. So I need to start cutting some pcb board… guess have the perfect tool for this :D.

* No strange noises, but the typical noise when idle.

Woodworking

I have a high respect and admiration for woodworking, and tough I have the tools (chisels, saws, planners, etc), rarely find myself working with wood. More commonly I build particle board furniture, and tough it’s not easy, I wouln’t call it woodworking.

This is a toys shelves project for my son. I could made the sides of particle board, but I wanted something special and liked the idea of a painted wood frame.

Tough this is a simple half-lap joint structure, It required a lot of work and tools (as always, much more than I expected… this isn’t a weekend project). One thing that makes it harder it’s the fact wood bars aren’t exactly the same width. Also I almost never can cut perfectly square; always had to use the chisel and/or file to correct the cut.

I did all with manual tools except rounding the edges; for that I did use a router. Also I did the all holes with my small microlux drill press.

woorworking_05

Not bad. It’s nice to see how practical considerations and a little of devotion cand lead to a beautiful design, without pretending doing something beautiful in the first place (I sometimes envy designers capabilities to create cool designs). May be it’s has to do with the way nature works.

Something about Delrin

Here is a design of a telescopic cover for the Sherline lathe  (please note this isn’t the full drawing).

Why I need that? 1. Because I hate having to clean and lubricate the ways after every use. 2. Because all these debris can increase wearing on sliding parts. 3. Because this is very desired feature on a CNC machine.

I made some delrin parts but drop the design. it I was more committed in doing something cool than functional. Probably it would work, but a simpler design was possible. The simpler, the better, so all these nice parts will go to the bag of sample parts or be reused later.

These parts looks simple, but there was a lot of hours involved in design and building. One good thing I learn about working with delrin was that, due to internal stresses of the material, you should do a rough cut of the shape of the part, and later finish all surfaces.

For example, to cut the straight bars in the picture, starting from a plate, a possible set of steps are: finish the edge of the plate, cut the bar and then finish the other three sides. The first bar below,  done this way, has a evident warp.

For the other two, I cut the bars slightly oversize and then did several set of passes over the sides, slowly getting close to the final size. This is a matter with thin parts; for compact and simple parts this is not an issue.

I almost finish the new design for the cover, so hope to begin the building phase soon.

Almost Back

First of all, I apologize for not answering comments. There are been nine months since I login to my blog.

I hate to speak about my personal life, but this time I will do an exception. Beginning this year I bought and move to a new apartment (rather old), left my work as software developer and devote to take care of my son (1 1/2 years now). As I like to do all by myself (I’m obsessive and maniac, I know), I start to refurbish the apartment (plumbing, new kitchen furniture, wall repair, painting, details, details, details…), and what supposed to be two or three months turns out to be much more. Also taking care of my son left me almost no time and energy left; indeed working as software developer was joke compared to housewife work. Actually, tough there still a lot of pending work, my working room is finished, so I plan to come back to my projects.

By the way it’s not my purpose to be dependent of my wife forever, so I hope to find some ways to live from what I love to do (a table saw kit and other things come to my mind). I plan to devote between 9:00 to 3:00 AM to my work (rest of the time I will be a housewife and continue apartment refurbishing).

So the next step will be mainly to assemble my mill and lathe, finish my cnc project-machines and clean my computers (I have a mess with my files). Also I will answer pending comments over the next days (sorry for the delay!).

CNC lathe limit switch and other things

I’ve been busy so there’s nothing new to show at the moment (this will change soon).  So in the meanwhile here are some old pics of the ongoing manual lathe to cnc convertion. I start this project with used Sherline parts (a not well cared bed, headstock and tailstock I bought on ebay).

– Using the manual lathe to drill to motor mount holes on the bed. I use some custom made aluminum blocks to raise the bed to the required height.

– Adapting the leadscrew thrust.

– A custom made nut to fix preload nut (I think this is better than glue). Please note that I bought cnc motor mounts only, not the full upgrade kit, so I must adapt the leadscrew also (this was a bit tricky).

– Making a limit sensor. Sure, this is not required, but it’s handy and nice to have. I use delrin and some floppy drive sensors.

– Limit flag and mount for the Z axis.

– A better flag. I hate this way of cutting metal sheet, but didn’t had the table saw at this point. I use scrap sheet metal from a pc case.

– Full assembly  of the limit sensor.

That is. May be a fixed sensor on the rear would be a better idea, but nevertheless this limit sensor works very nice. I must admit homing the lathe has something hipnotic.

Stand-by project revival

Ok, now that I have a mini table saw, a low profile vise and horizontal milling capabilities, I can continue working on my Sherline cnc lathe, specifically on the telescopic cover (I hate all those chips on the ways, and I hate having to clean them). Already had a design and some parts done.

As more machines means more space, I did some cleaning on my shop and leave only the most used tools on the table; 95% of the time I use the same accesories and tools, so It doesn’t make sense waste scarce table space on things I don’t use very often.

Going Horizontal

Today I finished a very simple accesory that turns the standard sherline mill into an horizontal mill, within seconds. It’s designed so it doesn’t get in the way of the table, so it can remain installed.

I don’t know why I didn’t figured this before… so nice. Will upload drawings in a week or so.

Drawings

This isn’t exactly the design I build, as I didn’t had a plate stock of the required size. This version cover all the riser block side.

Update (Jan 2014): By the time I’ve used this accessory I’ve found it has a design flaw; it flex more than expected (It had been very, very useful, tough). So now I think a 3/4″ plate should have been better.

Low Profile Vise

A tipical problem: I need to mill a slightly long part, let’s say, a 10x10x130mm bar. Sure, you can use the good Sherline vise and clamp the part by the middle, but vibration at the ends of the part is a problem.  So after getting inspired by this and this , I decided to build my own wide low profile vise.

Start point

First, I bought a pair of used step jaws. They are really high precision, and include two stop options. As I understand this jaw types are for Kurt type vises, the big brand in professional vises (of course my vise will be a joke compared to one of this vises, but that’s not the point).

Design

Design specs were:

  • Low profile
  • 4″ wide
  • Interchangeable jaws (must fit my Kurt 4″ jaws of course).
  • Should have stops.
  • Should be able to be used in the X or Y axis.
  • Should not require clamps for installing.
  • For light duty work (well, this cover Sherline use).
  • And, of course, a simple design.

I choose 1/2″ tooling plate for the base and 1″ square bar stock for jaw supports. As always, after some draft drawings I began the building process.

Building

Main steps in building this thing were:

  • Cutting to size and squaring the base plate
  • Milling T slots (easier than what I expected).
  • Cutting and squaring jaw supports.
  • Drilling a lot of holes (harder than what I expected).

Some parts appears in previous posts. Here are some pics.

And here’s the assembled and installed vise.


Testing

After clamping an aluminum bar I found a problem: front and back supports lift about 0.5mm after tightening; it seems aluminum over aluminum lifts, but t-nuts remains fixed. So after that I add a key to the fixed jaw support (previous pics show that); at least this will allow to keep alignment.

Installing it’s a bit tricky, as two of the clamping screws go below the back jaw support.

How much clamping force? I don’t know, but at least I was able to raise the whole mill holding the clamped bar with both hands (I was not able to take a picture of this). That’s enought to me. Here are my vise and the Sherline one.

Tightening looks, at first, a bit troublesome, as this requires to tighten 8 screws, but anyway it’s a less than a minute process, so I can live with that.

Final Toughts

Sure, this is a light duty vise, but I love the step jaws, the stops and the fact it’s low profile.

I must admit I would have like a larger back for the movable jaw support, but space limitations led me to the actual design.

This vise can be used to clamp small flat plates, but a simpler solution for this are Dave Hylands Fly Cutting Clamps. They are the best practical design I’ve seen fot this type of clamps, so for sure I will anotate this in my long list of some-day-I-will-do projects.

Chuck spider

The problem

Sometimes I have to turn small or thin parts in the lathe (a coin or a small pin, for example). There are two common problems with this parts: how to clamp them and how to get repeatibility. If my concern it’s not clear look the parts I need to finish.

Sure, I can clamp one of this parts in the chuck, but I can’t release it and place back in the same position.

The Solution

There are several alternatives to this issue. I choose what’s is called a chuck spider, something like a support between the chuck and the part. As the part get supported by the spider, you can get off the part, measure, and place back in the same position easily.

Design and Build

Instead of making only one spider and adjust deepth through a spacer, I opt for making three spiders: 2,5mm, 5mm and 7.5mm. Let’s the images tell the history.

To finish the cutting-off side of every spyder, I made an improvised shellac chuck (or “wax chuck”) , a classic watchmaker’s technique (btw, this is also a posible solution to the original problem!). I don’t have shellac wax, so use carnauba wax instead; this works fine for me. Here’s the finished set.

Testing

To avoid chuck jaws mark the aluminum surface usually I fold the complete part in strip of aluminum sheet, but this time I wanted to try something different, so I design and made some sort of reusable jaw pads.

Nice!

Overall

What can I say. Every Sherline user should have a spider, they are so great!.

Using the wax chuck was so nice that now I’m thinking on making one with self heating, so you dont have to take off the chuck and put on the stove to put/extract the parts.

I will add some drawings soon for the spider and the pads.