Tuesday, August 23, 2011

Another correction - Steppers

After some calculation as to the http://www.engineersedge.com/calculators/torque_calc.htm calculator for bolt torque I came up with an almost unbelievable small amount of torque needed for the Z axis steppers.  It is amazing how efficient a screw mechanism can be. So,to lift 10 lb, I only need 0.5 lb/in or 8 oz/in torque (0.5  lb / in = 8 oz / in). Similar goes for the VAT tilt, but adding to that gravity and I did not even make an effort to calculate it, I have just used lower spec motors that follow:

a 25 to 35 oz/in ( estimated by comparison - could not find docs for this particular model ) from a printer
no idea what this stepper is rated at (estimate is about 70 oz/in) , but if it fails for the task I will replace with the 180 oz/in on hand.

Tuesday, August 16, 2011

Goodies at the Sunday market

I ran into a few useful goodies at the local flea market:

a couple small NEMA17 stepper and an all important Emergency stop button from Fuji Electric.

The Stop button is of fantastic quality. It is barely used. How many times have you had to push the Emergency stop on daily basis? I hope to never use it, but if the need should arise, it is there.

How many fingers am I holding up?!


A small frame correction

After some consideration I have made a small correction in the corner (gussets) bracket location.

As you can see the bracket that holds the cross-member rail for the projector was moved to the top. I have discovered some flex in the joint and it was eliminated that way.

Also, as seen in the picture above, I moved the bracket from the outside to the inside, facing the projector, giving me longer movement of the projector all around.

To get a little more maneuvering room under the projector I raised the entire frame on 4 bolts ( like stilts), but you can use other, equal height pieces you find around the house.


Monday, August 15, 2011

Mounting the Dell 5100MP

A little more progress made. I have mounted the projector to the frame.


Washers 18mm x 1mm M6 - 10pcs.

Socket wrench + 10mm socket.

Screwdriver ( No, not the one with the Orange Juice! It is too early to drink! ) depending on the M3 bolt heads.

M3 x 25mm bolts - 3pcs.

M6x20mm bolts - 3pcs.

Standoffs - 18mm x M4 - 3pcs.

For the purpose I dug up an old aluminum heat sink (120mm X 150mm) , but you can use an aluminum flat piece 4mm thick and with a proper size for your projector mounting holes. Disregard the 90 Degree bend.

The easiest way ( since projector manufacturers do not provide you with a bolt pattern like water heater manufacturers do) to create and transfer the mounting hole location is on a piece of paper. Mark the hole locations and attach with tape to plate ( after you center it, of course ), and drill the holes ( in my case on the 5100MP they are 3mm ) a little bigger ( 3.2mm ) than the bolts to be used. Check for fit. Check that no vent or air holes are blocked ( read further below and you will see ).

Then drill holes for the bracket to frame bolts 6mm ( similarly a little bigger that the bolt size 6.2mm).

As in the post about the Power supply, get more washers than just needed ( these are also 18mm, but for the M6 bolts ) and M6x20mm bolts.

I used 3 M6 in a horizontal pattern - did not follow some specific distance between them, just two near the end and one in the middle.

As seen I had to add spacers, because the mounting plate covered a vent hole on the bottom of the projector and also to clear the washers and nuts used to mount the plate to the frame.

I had to also countersink the M3 x 25mm bolts a little(2mm)with a 5mm drill bit, so they screw in further in the projector frame and I have a more secure projector-plate connection.

And the end result looks like this:

Nicely done! Now you can get that screwdriver with Absolute.

Sunday, August 14, 2011

Stepper Motor Drivers

And speaking of the drivers:

I have chosen the IMS drivers for their reliability, simplicity, size and characteristics .  I already have them in my CNC mini mill and am content. I have worked with them before at a CNC machine shop.

I had used all 4 IM483 and only had exactly 2 IM804 left. The 804 can handle higher input voltage ( 24V to 75V ) and output current is at 4A RMS.

For those who are familiar with the IM804: Yeah, I know it is overkill, but for the fact that I did not have to spend more money, they will do the job nicely. BTW: IMS was acquired by Schneider Electric a few years back - http://imshome.com.

Power Supply for the steppers

I have chosen an old power supply from HP 32V 2.2A for the steppers since the NEMA17 is not over 0.7 and the NEMA23 will be limited to 1A. I have chosen to mount it temporarely via some washers in the channel and brackets.

Washers - wide 18mm(5mm internal)x1mm ( I will use them all over the place so get at least 50)

Bolts - any head 20mmx4mm will do ( again take at least 20 )

Brackets - 40mmx40mm right angle for wood frame

Held in place by zip ties.

You can get a dedicated power supply and depending on your motors choose a higher rated Amps.

Rule is generally add your stepper driver limit +5%~10%. No point in wasting money on more power than that.

In my case I will limit the Amps via the stepper drivers to collectively 2A and it will not be even at 25% duty cycle (calculating from 8sec exposure and 2sec tilting cycle).

Saturday, August 13, 2011


Ok, here is the tools needed and assembly of the frame:

Preferably a quality socket 13mm ratchet driver (Craftsman):

A flat surface (Yes, there was a reason for the Faux Granite stoneware tile and the clean-up of  my workbench) Check!

The first two joined together!

 It is a little harder than 80/20 Extrusions, because the bolts and nuts travel in a slot cut into the brackets(gussets).

OK! This is starting to look weird?! I think I've seen this before. Maybe its Deja-vu.

Does anyone recognize this? Anyone?

Of course there is a reason for all this! If I choose to get parts from JR, they will still be compatible.

As I don't have access to a full machine shop, I prefer to keep everything store bought with minimal modification.

The dimensions are a little different, but the top build area should be easily adaptable.

It is a strange feeling to see this all done in about a half an hour (excluding the time to stop and take pictures). With any other frame I would have had to fit, mount and measure, and cut, and fit and measure and so on.

I have, on purpose,  extended the projector horizontal mount (X axis if you will) travel a lot. It can accommodate a wide range of projectors if I choose to change it at some point.

Friday, August 12, 2011

Bosch-Rexroth Goodies

The aluminium (or aluminum)extrusions and the service from Bosch - Rexroth proved no less than pure perfection! I have received the extrusions cut to size within 0.1mm or better and packaged well. I have received exactly what I ordered, on time (was quoted 3 workdays) in 2 workdays. There were no missing parts, wrong parts or defective parts. Yes, a little expensive, but all worth it when comparing the prospects of finding a welder, cutting, machining, priming, painting, wrong sizes, redo's etc.

Plastic End caps and Corner Brackets(gussets).

 Whoaa! Shiny stuff! Put on your sunglasses before clicking!

BOM of the extrusions:

#1(one pictured)     9pcs. of 420мм – Extrusion 40х40 L – for the frame and one for the projector

#2,#3,#4,#5      4pcs. of 400мм – Extrusion 40х40 L – for the corners

#6     1pcs. of  320мм – Extrusion 40х40 L – for the VAT crossmember

#7    1pcs. of  305мм – Extrusion 40х40 L – for the Z axis THK KR20

#8,#9    2pcs. of  160мм – Extrusion 40х40 L – for the projector X movement

#10    1pcs. of  105мм – Extrusion 40х40 L – for the VAT tilt LS3-1 mount

Pictures of the VAT tilt slide.

It is a little known fact, that the Imperial 10-32 bolts and the M5 Metric bolts are very close to each other,  some people call them "Compatible". So I have managed to secure the stepper with a M5 bolts in the NEMA23 motor mount. Bolts are M5 x12 "Inbus" (Allen Head) motor mounting and M5 x 25 (the  black ones) are for slide to frame.

And of course the VAT tilt slide photos,and the proof of the above statement:

Pictures of the Z axis

Once I have a "Clean slate" to build on, might as well use it for some photos:

Z axis THK KR2001a-0200L

Build Base

Welcome to the build log for a 3 DLP rinter.Without further ado we begin.
I like to always start a project with a cleanup of the build table, organizing my tools, have something to write with and onto. It helps me clear my head and refocus on the subject at hand.For this project I had in mind to lay a granite surface plate I had, but it proved a little too small for the job.
Looking for alternatives, I landed at a porcelain stoneware floor tiles 60cmX 60cm (24" x 24" ). They have a flatness from manufacturer of 0.1mm/m, giving me about 60 microns flatness overall.

Friday, August 5, 2011

What a title!


Build log of a "3  DLP  rinter".

I'm sure to step on someones toes, but I assure you it is ALL ABSOLUTELY INTENTIONAL.

Hope there will be lots more copies replicated all over the world.