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.