3D printer progress – assembly and test

At this point the frame is largely assembled. The carriages are mounted, the heated bed is installed and things actually move (at least manually).

I used a MK2A 300x300mmaluminum heatbed and had to move the motor motor and leadscrew mounts. The motors need to move out from the back as well. This is a good thing as otherwise the motor move would interfere with the 3×3 triangles. Flipping them over fixes that issue. However the smaller top 3×1 brackets do need to get trimmed for clearance. This was a quick trip to the band saw. .

The first piece to get moving is the bed elevation. The critical part of the motor alignment is at the bottom end. Need to get the motors under the drive screws. Sight along the frame to see that the screws are parallel to the legs in both directions and then tighten them down. The safety stops in the firmware need to be over-ridden as normally you can’t move the  axes to a negative position. In this case, negative is UP . So in Configuration.h make the changes as shown below to get the over-ride for testing and the homing directions:

// ENDSTOP SETTINGS:
// Sets direction of endstops when homing; 1=MAX, -1=MIN
#define X_HOME_DIR -1 // left
#define Y_HOME_DIR 1 // rear
#define Z_HOME_DIR -1 //top

You need to comment out the block below. It prevents the use of the max direction endstops. It took a while to find as I was troubleshooting why X&Z would home nicely but Y would not do any homing movement at all.

// Disable max endstops for compatibility with endstop checking routine
//#if defined(COREXY) && !defined(DISABLE_MAX_ENDSTOPS)
//#define DISABLE_MAX_ENDSTOPS
//#endif

#define min_software_endstops false // If true, axis won’t move to coordinates less than HOME_POS. — allow for testing
#define max_software_endstops false // If true, axis won’t move to coordinates greater than the defined lengths below.

This will allow moving the bed upwards under manual control.

I also made the initial settings for the stepper calibration. I am using 32 step microstepping (rather than the more typical 16), 8mm pitch threaded rod and a Micron EME cobra extruder. So the step calibration at this point looks like:

#define DEFAULT_AXIS_STEPS_PER_UNIT   {200,200,812,1168*2} // 32 microstep 16 tooth gears, 8mm acme rod & micron extruder

Belt installation was straightforward, but make sure to place a screwdriver blade behind the nuts for the clamp bars before inserting the screws. It is far to easy to push the nuts back and have them fall out as you attempt to clamp the belt to the carriage.

Currently all 3 axes are moving, and homing. Calibration still needs to be checked.

I was also configuring the temperature sensors to get the thermistor for the heated bed to work and get ready for print head testing. I am also running a thermocouple for the print head. I want to run thermocouples for the print head to use high temp plastics such as Nylon. The low output signal from a thermocouple requires an additional amplifier or special A to D convertor.  I had purchased the Max6675 thermocouple digital adapter. However, it turns out it is not compatible with having a 128×64 display!!! There are shared conflicting pins. NUTS!. Now I have to order some AD597 adapter analog boards (and wait for them to come form China, as I could not find any stocked in the US).

When I started the project I downloaded the Marlin software directly. I would have been better off starting with the package on the d-bot page (or at least using the configuration.h file). It was in a line by line comparison that I found the Y axis homing culprit. http://www.thingiverse.com/thing:1001065/#files   and select d_bot_marlin.zip

Dresser glue ups – diagonal squaring breakthrough

The dresser frames are now all glued up. As you might expect there is an experience curve here with the last one going most efficiently.

I also reached the conclusion that I would not be cut out to be a surgeon. The complex assembly with the time pressure to get everything done within the time window for the glue is stressful. This turns out to be quite vigorous exercise. I was sweating bullets by the time I was done each time (stripped to the waist looking more like Dr Pol pulling a calf than anything you would see in Fine Woodworking) . Lots of moves and also the physical effort of getting the pieces in place and clamped securely in time. With PVA glues you only ave about 15 to maybe 20 minutes to get everything fully clamped or it will be stuck in a BAD position. Even with the ends pre-assembled there are over three dozen pieces to get in position and clamped in that time.

Even with mortise and tenon joinery with nice big shoulders the case will be “out of square” when first assembled. As you can see in the previous post there are pipe clamps o the diagonals to pull things in line. However they are a pain to manage , requiring 2 people and easily falling off. Today I though I would use rope as a sort of “Spanish windlass” to pull things in , but I don’t have much in the garage. So I grabbed a couple of ratcheting tie downs out of the truck and used them first. WOW this is EASY!!! They work great whether attached to the clamps or wrapped through the corners. I am sure others have thought of this before, but I have not seen anything like this posted in woodworking magazines or when I was in the Wisconsin Woodworkers Guild.  Here are a few shots of 2 different frames using this technique.  My tolerance for these is to get within 1/16″ on the diagonals. If not this close, fitting the flush drawers will be a horrible task.  You can easily ratchet them tighter and pull the frames square or back off a notch if you have pulled too hard.  Plus you can weave them through the pipe clamps and other clamps without being stuck in an unreachable position as when using clamps to do this.

Asian Inspired Sous Vide Mixed Ribs

Asian inspired mixed Ribs

I wanted to make some asian style beef short ribs. However the local store did not have any . However they had both boneless beef short ribs and baby back pork ribs on special. Since I wanted to try to do both sous vide,  I decided to do both mixed. I did not have scallions, but remembered seeing some red cipollini onions sprouting in the garden from some I missed last fall.

Marinade / cooking sauce

4oz orange juice concentrate

2 TB shaved fresh ginger (we keep ours in the freezer – easy to slice)

3-4 TB chopped green onion tops or scallions

1/3 c Soy sauce

1/4 c Rice wine vinegar

3 TB Hoisin sauce

1 tsp Chinese 5 spice blend (Penzey’s)

1/2 c brown sugar

2 TB sesame seeds

1TB sesame oil

1 scant pinch red pepper flakes.

Mix the sauce ingredients and bring to a simmer for 5 min.

Cook

Slice the baby back ribs 3/4 of the way through for more surface area

Place the meat in 2 vac bags with the sauce. Carefully remove the air and seal without pulling out the marinade

Seal and  place in the water bath

155 degrees F. for 7 hours

The pan for the sauce holds the ribs down and reduces evaporation

Bake the ribs in an open pan at 375 convect with 1/2 of the juice for 15 min . Flip the ribs over.

Boil down the rest of the juice to a thick sauce consistency and brus on the ribs after they have been flipped

Bake another 15 min and then serve.

Conclusion

The pork ribs were perfectly done. The beef ribs needed quite a bit more time. Both were delicious, but I would like the beef ribs to be more tender. Other recipes had the beef ribs at 20-48 hours at 135-170 degrees. So more experimentation is required for them. Teal (miss picky) loved the flavor and the pork. .

 

D-Bot 3D printer frame assembly

The printer frame is built out of V-slot linear rail http://openbuildspartstore.com/v-slot-linear-rail/. This is similar to the 80/20 and Bosch rails I have used on the CNC router but with one crucial difference: the slots are V shaped a the top. This allows rollers to run in the grooves to provide the motion without having to add linear rails like I used on the CNC router. This is far lower cost, but also lower precision. However, the test prints I am seeing from a friends unit look great.

The precision of the cuts is critical to rigidity and squareness of the printer. You should use a non-ferrous metal blade  in either a chop saw or radial arm saw. I use a Bosch PRO1080NF 10-Inch 80 Tooth TCG (triple chip grind). This has served me well for several years.  When using the radial arm saw as I did be careful to prevent over-feeding. The stop system on my saw makes for nice repeatable cuts.

Once cut, the ends of a number of the rails must be tapped for M5 screws. The extrusions already have proper sized holes but this is still tedious if using a regular plug tap. This is is where a “gun” tap or “spiral point” tap which is designed for through hole power tapping comes in very handy. I started using these for the 100’s of tapped holes on the CNC router. I used plenty of cutting fluid and a hand drill with the tap chucked lightly to tap the holes. Practice first and have some spare taps on hand prior to doing this on the v-rail. Snapped taps are darn near impossible to remove from aluminum.

3D printer electronics initial setup and test

For the D-Bot 3D printer http://www.thingiverse.com/thing:1001065, I am using a Rumba controller with DVR8825 stepper drivers. The display is a Full Graphic Smart controller (128×64). I ordered these from Amazon.

The boards were received with NO instructions or pin out labels to get the ribbon cables connected correctly.  If the display is flashing and beeping on power up it is in one of the several wrong connector orientations that are possible (and I tried several).  Connect them up like this:

You must load the firmware for the board which involves:

  • Setting up the Arduino IDE
  • Downloading the Marlin source code
  • Downloading the driver for the display and installing it as a library
  • Downloading and installing the USB port driver for the board

Next the Marlin source must be configured for the board and setup. Much of this requires removing the double backslash // that comments out particular lines in the header files.

Boards.h

Find the Rumba in the list and write down the exact # define value

Configuration.h

Rumba config

// The following define selects which electronics board you have.
// Please choose the name from boards.h that matches your setup
#ifndef MOTHERBOARD
#define MOTHERBOARD BOARD_RUMBA
#endif

Display config

// The RepRapDiscount FULL GRAPHIC Smart Controller (quadratic white PCB)
// http://reprap.org/wiki/RepRapDiscount_Full_Graphic_Smart_Controller
//
// ==> REMEMBER TO INSTALL U8glib to your ARDUINO library folder: http://code.google.com/p/u8glib/wiki/u8glib
#define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER

CoreXY config

// Uncomment the following line to enable CoreXY kinematics
#define COREXY

Disable the extruder drive safety

In order to make the extruder drive without the temperature control hooked up, you need to temporarily comment out the safety. Remember to remove the comment slashes later when you are ready to run filament through it.

//this prevents dangerous Extruder moves, i.e. if the temperature is under the limit
//can be software-disabled for whatever purposes by
//#define PREVENT_DANGEROUS_EXTRUDE

configuration_Adv.h

Dual Z config

remove slashes in front of:

#define Z_DUAL_STEPPER_DRIVERS

Pins.h

//Dual Z config  insert in the Rumba pins section:

//to use Z_DUAL_STEPPER_DRIVER in Marlin
#define Z2_STEP_PIN 26
#define Z2_DIR_PIN 25
#define Z2_ENABLE_PIN

The second Z stepper is plugged into what is normally the E1 (second) extruder driver slot.

Compile and download the firmware. Some sources recommend moving the power jumper to USB from standalone if you are having difficulty with downloading.

When downloading you will see the yellow leds on the rumba board blinking rapidly for about 15-20 sec . Then you should see the display show the Rumba Ready screen.

Stepper driver setup

Set the dip switches under each motor driver for 1/32 microstepping. This is all on (towards the middle of the board).

Insert the stepper drivers with the adjustment pots towards the connectors (and the heat sinks away). Like this. You can see the dipswitch for the 6th driver slot on the right. :

Now calibrate the current for the stepper drivers BEFORE plugging them in to avoid overheating. See: https://www.pololu.com/product/2133 for great instructions.

Now power off and plug in the steppers. NEVER plug or unplug the steppers while the power is applied.

Restart and test the steppers.

Press the rotary switch and then select the Prepare menu. Now scroll to the bottom and select Move Axis menu. Now you can select a step amount (e.g. 1mm) and then select the  axis to move.

The Z axis motors should move together in the same direction. The other 2 will move for either the X or Y (opposite or together respectively).

Now I have all 5 stepper motors running at will and the control electronics basically working. The electronics are ready to mate up to the mechanical pieces.

 

 

 

New 3D printer project

I have not written much about 3D printing. The CNC router had a print head added at the end of the year. This was not what I would call a great success. Mounting hte print head assembly, a Micron EME, was fairly easy, but I also had to add the print nozzle temperature controller, which had to be close to the head as I used a thermocouple for temp sensing de to wanting to use high temperature filaments. I am using Mach4 for the CNC router controller. It has NO 3D specific functions built in despite a stock 3D printing profile. So there is no temperature control for the print head or print bed provided. Both of which are are more important than I would have guessed.

The print head extruder stepper is set up as the A axis. I have the nozzle temperature externally manually controlled as required for each type of filament. Currently I am running PETG from eSun. The print bed is a sheet of glass (cutting board from amazon) with blue painter’s tape to aid adhesion. The CNC router does not have a heated bed, but I can aim a heat gun with diffuser under the raised glass build plate to have a sort of heated bed. The bed needs to be in the vicinity of 80 degrees C to avoid the parts warping and pulling away from the bed.   The heat does make a HUGE difference when trying to print anything over about 1-2″ across.

The printing required considerable tuning and testing of the parameters. I am using the open source program Slic3r to do the slicing to prepare for printing. It took about 20 test objects to get things reasonably dialed in from scratch

3D print underway.

Finished product prior to trimming and clean up. This was at 0.35mm layer height.

Dresser Rails

Here is one more shot of the ends being glued up. This is another case of never having too many clamps of flat surfaces in the shop. The ends are clamped at very joint and spaced up above the work surface for the first 2 hours. They are also checked for squareness. which is pretty good given the shouldered mortise and tenon joints, but a couple needed to be tweaked of the last 1/16″ on the diagonal measurements (your true test of squareness on a large piece).

With the dresser ends glued up and the glue squeeze out cleaned up it is time to run my attention to the dresser rails and dividers. The rails, for lac of a better term, are the horizontal dividers between the drawers.  The dividers are the vertical pieces between drawers on the same level. The rails and dividers are part of the overall frame structure. They are not however the primary support for the drawers. That is done by the runners which are a future topic.

For the rails, the mortises were cut on th CNC router, but this time I squared up the holes with a chisel. In many cases this is actually less effort than rounding off the tenons. The mortises were cut with a 1/4″ router bit. So there was only 1/8″ to clean up on each side.  Start with the cross grain cuts. This is normally 2 strokes. Here it is shown on the top mortises.

Note the chisel is angled. This makes it much easier to keep it in the corner. Yo are trying not just to clean up the cross grain side but also lightly score the fibers for the cut along the grain on the adjacent side. The cut along the grain requires more effort. I will press down with my chest or chin to assist in paring the cut. I am not a fan of using a mallet for this it is too easy to dig in and make a mess of the mortise 

Now with the mortises cleaned up, it is time to fit the tenons. There is a small amount of work to be done for final trimming with the rabbet plane.  The rails and dividers are also sanded to final thickness on the drum sander to make for an exact fit in the half lap joints. Then the first dry assembly is started.

So far so good. The pipe clamps are the only practical means of clamping something this wide and gently squeezing together the assembly. Note the couplers in the pipe clamps. I have a selection of 3,4,5 foot 3/4″ pipes and when I need long clamps as I do now the couplers join the sections. You can also see that the joints for the rails and dividers are half lap joints. These were cut again on the radial arm saw with the blade set for 3/4″ width (that has not changed for the hundreds of cuts). Here is a close up of the smaller dividers and joint.The next step is to gut the dadoes in the rails. The drawer runners fit into these with tenons on each end. One of the fine poitns is tha the runners are not level with the rails but slightly raised by about 1/16″ . This is so the drawer can slide in without wearing on the rail and having a gap on the bottom that is closer in size to the side and top gaps.

Here is a shot from a previous project which is a very large chest / wardwrobe with cock beading around the drawer openings. Note I love the kids but I am NOT going to do 3 cockbeaded dressers for them – way too much work.

Cockbeading is an applied bead around each drawer. It can either be on the frame or drawer. Here is a shot of the whole wardrobe. You can see it as the raised profile around each drawer.

The drawer runners are slightly raised compared to the rails. You can do this by either offsetting the tenons on the runners as I did in the wardrobe, or by offsetting the dado in the rails which is what I am doing for the dressers.  For the dressers, teh rails are all carefully arranged and marked for which side is up. Making mistakes now is critical.

The table saw is set up to make the dadoes with:

zero clearance insert around the blade for support of the piece when pushing through.

Feather board to push the rails against the fence.

Block to hold the stock down. Note in the setup the piece of paper as a spacer and rounded leading edge to make feeding easy. 

The dado is offset by about 1/16″ and a test block is run.

One final double check of the orientation of the rails

Running one of the rails through.

Now I have the rails ready for the runners. Next step will be making the runners and inner dividers that go between the drawers.

Dresser End Grid

The end panels have a decorative “grid”. This add interest to what would otherwise be a plain end panel set in the frame. This sort of decoration is common on Craftsman style pieces.

There will be a 1/4″ panel set behind the grid which will git into the rabbets down each leg and behind all of the end rails and grid pieces.

The joints are half lap style. The end rails each received pockets for the vertical dividers. The pockets are 1″ wide, 3/8″ deep and 1/2″ high.  This was done on the CNC router. Apparently the pieces lifted a bit off of the bed of the CNC router in the process of clamping them and I have to deal with slightly varying depth pockets.

 

The vertical slats then have the tenons cut. This is another series of cuts on the radial arm saw.  The tenons are 1″ wide and nominally 3/8″ thick (0.375″).

 

 

 

 

 

 

 

 

 

 

 

When making many repetitive cuts like this it easy to lose track and miss an end. I have learned to always neatly stack the pieces up and do a quick visual check to see if I have everything cut the same. If everything is uniform, then I can proceed to the next step and tear down the stops and setup and get ready for the next cut.  At this point the vertical divider tenons are complete and I can check them in the end frames and move on to the next steps.

The horizontal dividers fit into partial half lap joints in the vertical dividers and mortises in the corner posts. The cuts in the vertical dividers could again be done on the CNC router but the clamping would be too time consuming. Given that the back side is concealed, the dado blade can be used (again).

There are 2 cuts to be made in each of the vertical dividers. I use a stop block and a removable spacer block. The spacer block is 2.25″ which is the spacing between the 2 cuts in each of the vertical dividers.   First cut.

 




 

 

 

 

 

 

With this type of cut the radial arm saw wants to strongly self feed. In order to reliably not cut all the way across the divider slat, I added a stop on the cross arm of the saw. Not very elegant, but the clamp does the trick for the 24 cuts. Below it you can see the second cut has been made without the spacer black.

 

 

 

 

 

 

 

For the opposite side, slats the mirror image of the setup is needed. However due to lack of clearance beneath the radial arm saw motor an extra spacer block is needed and held in place by the spring clamp. Rather than re-measuring. one of the test pieces is put in place and the saw advanced and blade rotated to line up in the dado.  Then the stop and spacer are clamped in place. 

The max depth of the pockets is 0.4″ so the tenons will all be cut to this thickness and then trimmed to fit with a rabbet plane.  This Lee Valley Veritas Medium Shoulder Plane is one of my favorite hand tools. I bought one as soon as it came out and it has been my “go to” tool for cleaning up mortises and rabbets for over 10 years. Far better than the Stanley 78 and similar that I had been using and much more manageable than the large shoulder planes.

 

 

 

 

 

 

 

 

 

 

 

Now I have the pieces for the ends dry fit assembled.  As you can see, I have labeled all of the parts for final assembly. At this point everything is finish sanded. I have not yet decided on whether I will do a finish first and epoxy assembly as I did with the beds or conventional glue up and then finish or something in between.


 

 

 

 

 

 

 

 

 

Right side up.

 

Dresser Project Legs and End Rails

With the first set of mortises in the corner posts complete, it is time to move on to the second set.

As I started cutting the test pieces it became apparent that it is critical to use the exact actual size of the posts or the end mortises and rabbet for the panel wont line up. The legs are a nominal 1.5″ wide but after sanding are actually 1.45″ wide. This is enough to cause the end decorative piece mortises to intrude on the rabbet for the end panels.

Looking back I should have cut all of the rabbets with the mortises for the end pieces and not with the first set of mortises for the front and back supports. This results in some extra hand work and there was one leg that had to be redone all together.

When manually making the rabbets and mortises, my setup always take into account the fact the at the pieces are not EXACTLY uniform and the best reference edge is used to minimize error and achieve uniform joints. On the dresser the natural reference edge on the corner posts is the inside corner.

Additionally the rabbets should not be done as a single pocketing cut with the CNC router but rather first a skim cut should be made to prevent blow out or chipping along the edge.

Video of the second set of mortises being cut: https://youtu.be/G0lsWLeAlKk . The photo below shows the corner post after the second set of mortises has been cut. The saying on my coffee cup has never been more true.

corner post 2nd set of mortises

Now we move onto cutting tenons for the end rails.  My favorite way to cut large numbers of tenons is to use a stack dado set on the radial arm saw.

This is the primary task for the smaller 10″ radial arm saw. The large one (14″) is used almost exclusively for cross cuts. Note that both share a common fence and top system. Radial arm saws can be purchased for almost nothing nowadays. The big one was salvaged from a school and purchased for $50 (and then completely overhauled).

Double check that the saw is cutting exactly squarely. This is best done by taking a test piece that has been ripped for exactly parallel sides and a square end. Then make shallow rabbets on each side. If the cuts line up on both edges you are square. This is quite sensitive and uses less stock than the normal cut and clip technique. You can see the test piece laying on the top between the saws.

The stock must be of uniform thickness. The best approach is to ensure that all of the stock was planned in one batch or better yet sanded to final thickness in the drum sander as we did with the legs.  It takes a bit of fiddling with the height adjustment to get the tenon thickness right.

I have added a digital readout to the height adjustment of the radial arm saw to make this easier . After each test cut adjust the height by 1/2 of the thickness correction (e.g. if you want a 0.25″ thick tenon and the test piece measures 0.28, adjust the blade down by 0.15″. However always be sure to finish the adjustment by raising the blade to take out any play in the mechanism which would result in decreasing thickness cuts as the arm settles down.

The cuts are all made with a stop block to ensure repeat-ability.  Note that the sacrificial wood stop block is notched on the bottom to allow room for sawdust. The grey stop block on the left holds the position. If only using one block, a spring clamp would not be sufficient. Then I would be using 2 hand screw clamps as using only one will typically slip on repeated cuts.

Here is one of the bottom rail tenons being cut for thickness.

Here it is being cut for height.

The mortises were cut with a router and rather than squaring all of them off with a chisel, I typically prefer to round over or bevel the tenons. THe base of each tenon corner is nicked with a pull saw and then a couple of strokes with a chisel removes the rest as seen below.  This is one of the top end rails.

The end rails now need notches for the decorative frame work and this is done again on the CNC router.

Here are the ends test fitted.

Today’s work will be Fitting the decorative pieces on each end 


Dresser project legs

The legs are the first set of components to make. The rail tenons will fit into the mortises on the legs. There are a lot of mortises to cut. 9 per leg, 4 legs per dresser and 3 dressers make for 84 mortises of various sizes. This should be a perfect item for the CNC router.

The legs are cut from 8/4 quarter sawn oak.  I have a number of planks remaining from Wisconsin WoodWorker’s Guild LogFests where we milled and auctioned off many logs felled by our group or donated. This was an “urban wood” project. These have been air drying for a number of years. The Red Oak is perfect, the White Oak has more loss as it was not only more irregular to start with but is also prone to internal checking when air drying at home.

The pieces are cut to rough length first, then planed and jointed. Here I am jointing a slab on my 125 year old Colladay 16″ jointer.

The legs are then sawn to width and then run through the drum sander. This not only saves time later but also makes them uniformly square.  We used 80,120, and then 200 grit when sanding. Teal handles the outfeed. and I must be careful at the start and end of a set of sides that I don’t create an “I love Lucy” moment for her with pieces coming out faster than she can remove and stack  If this is not familiar see the “chocolates episode” : https://www.youtube.com/watch?v=8NPzLBSBzPI).

They are next cut to final length. This should be done after sanding to minimize snipe in the finished pieces.  The drum sander is a great tool for large furniture projects and especially where you want to be able to cut repetitive joinery such as tenons or dovetails as you end up with stock of very uniform thickness. Better yet for projects where you pre-finish before assembly as I have done with the beds and other projects.

Now that all of the pieces are of uniform width and length it is time to start routing the mortises. The dressers are symmetrical front to back. This means that I can cut the legs as pairs (front right – rear left, front left- rear right) as sets minimizing the number of cuts to lay out and chances for error.

The only problem at this point is I cannot get VCarvePro to properly import the legs to lay out the mortises. I had to redraw them rather than import the legs or faces from SketchUp.

At this point I have all of the mortises cut on one of the sides of each leg (2 layouts). Next will be the second side of each leg.

Routing and the leg clamped up on the CNC router.

Mortised legs.


The pile of other exterior components.