Introduction: Photogrammetry HID Tool
Update 5/2/19 - I’ve uploaded the initial application Screen Captures, from Recap, using the turntable tool. The added info is displayed in a new step added to the end of this Instructable.
This Instructable / Design Concept, is meant to assist the translation between 2D images and 3D modeling algorithms by upgrading a turntable into more of a HID (Human Interface Device) scanning tool.
My motivation to design a tool that will increase a modeling algorithm’s ability of translating images with a high degree of accuracy, is to decrease the amount of human image alignment. Accurate models of non-geometric shapes are hard to achieve by pushing and pulling polygons. With the right tools, DIY Photogrammetry allows the import of accurately modeled, complex organic meshes into my CAD program.
- A graduated rotating scale around the turntable’s perimeter has been incorporated to assist with uniform manual rotation.
- The turntable’s deck plates and bearing, are made to accommodate heavy model loads.
- Three aluminum legs radiate from the lower deck plate to stabilize bulky scan models. Each leg is equipped with a leveling foot bolt.
- The top deck plate features a column and large transition coupling to support heavy models.
- The transition coupling permits attachment of custom built, user defined, mechanical devices to support different types of modeling subjects.
- A model support column is 11.5” tall is included to permit photography from beneath without re-positioning the model.
The graduated scale is a Tailor’s Soft Measurement Tape glued to the 36” circumference of the top deck plate. Using the 1/8” marks, 288 revolve graduations of 1.25-degrees each are achievable.
Weight capacity is dramatically increased using ¾” (23/32”) BC plywood turntable decks, sandwiching a 12” diameter turntable bearing rated at several hundred pounds.
The ½” coupling nut attached to the top deck plate can transfer significant weight and side loads to the hefty supporting structure beneath.
Bulky and offset center of gravity stability is achieved using three out-rigger legs of 1” aluminum square tubing. On the end of each leg is a ¼” rivet nut and ¼” bolt used to level the turntable assembly. For very heavy loads, a round PVC cap fits between the three legs. Load force is transmitted to the cap through direct contact with the lower plywood plate. The leg bolts are adjusted to level the suspended load.
Rubber feet have also been attached to the aluminum legs, under the deck plate, to provide skid protection.
The threaded coupling nut serves as a mechanical transition for attachment of specialized hardware (designed by user) to secure different types of scan models. Examples would include a metal spike, alligator clip, a metal crossbeam, a flat plate, glue stub or whatever type of securing device is needed by a modeling practitioner.
I’m going to assume that people interested in 3D printing and CAD might not have a router table or drill press. For their sake, I’m going to present an Instructable using techniques that require only an electric hand drill, jig saw and basic hand tools. For those of you that are equipped to construct the next generation of a Mar's Lander, just gloss over the features and concept. You already know how to do this.
I’ve included many features with this turntable design, for the purpose of letting you choose what features you need. So, leave off anything you don’t need and add feature ideas of your own. For the first time in my life, I’ve broken "Big Al’s" number one rule of design, by making this Instructable an excessive conglomeration of possible features.
“Any intelligent fool can make things bigger or more complex…It takes a touch of genius and a lot of courage to move in the opposite direction.” – Albert Einstein
Materials and Hardware
12” x 24” x ¾” (23/32”) BC or Lauan Plywood (lowes.com item# 6654)
12” Diameter Turntable Bearing (lowes.com – item# 383405).
Three = 1” x 1” x 16” x .125” wall thickness, Aluminum Square Tubing (onlinemetals.com – 48” of item# 18014).
Three = ¼” – 20 Steel Rivet Nuts (I would suggest an assortment pack (for future projects) from ebay.com. Grip range isn’t important since the nuts won’t have pull out forces applied).
Soft Tape Measure (amazon.com)
Three = ¼” – 20 x 2.5” Zinc Plated, Carriage Bolts (lowes.com item# 63334)
One = 12” length of ½”-13 All-Thread
One = ½”-13 Coupling Nut (lowes.com item# 142075))
One = ½”-13 Hex Nut (lowes.com item# 63304)
One = ½”-13 Nylon Insert Locking Hex Nut (lowes.com item#63406)
Two = ½” Flat Washers (lowes.com item# 63309)
One = ½” Fender Washer 1/8” thick or two ½” fender Washers 1/16” thick.
Six = ¼”-20 x 1.5” Long Hex Head Bolts (lowes.com item# 63312)
Six = ¼”-20 Hex Head Nuts (lowes.com)
Six = ¼” Flat Washers (lowes.com)
Six = ¼” Flat Washers (lowes.com item# 63306)
Three = ¼” – 20 x 2.5” Grade 8, Hex Head Bolts (lowes.com)
Three = ¼” – 20 Grade 8, Hex Head Nuts (lowes.com)
Five = 2 ½” Long Deck Screws Hex Head Bolts (lowes.com)
Eight = #8 x 5/8” Phillips Pan Head Sheet Metal Screws (lowes.com)
Eight = #8 Flat Washers (lowes.com)
One = 9.5” length of ½” PVC Pipe (lowes.com)
One = 2” PVC Cap (lowes.com item# 23920)
New Paper Envelope
Card Board or Heavy Paper 7” x 1”
Spray Can of Grey Primer (lowes.com item# 1026826)
Spray Can of Matte White Paint and Primer (lowes.com item# 1026724)
3/4” x 4” x 12” Any Scrap Wooden Board or Plywood Section (for sanding only)
Can of Spray -or- Brush On, Contact Adhesive (lowes.com item# 275900)
Three = Self Adhesive Rubber Feet
Coarse Sand Paper (lowes.com item# 470333)
Fine Sand Paper (lowes.com)
Masking Tape (lowes.com)
1/8” Drill Bit
¼” Drill Bit
½” Paddle Bit
½” drill Bit (optional)
Sharp Nail or Awl
7/16” Socket Wrench
¾” Socket Wrench
Adjustable Crescent Wrench
Staple Gun (optional)
#2 Phillips Screwdriver
1” Wide Putty Knife
Large Flat Tip Common Screwdriver
Using the yard stick and pencil, draw a single line across the exact middle of the 12” x 24” piece of BC Plywood. This will create two 6” x 24” segments (1).
Use a black marker to label your bearing as I have, so there is no confusion during layout or assembly (2 and 3). These areas of the bearing will not be seen after the top and bottom decks are attached.
Lay the Bearing so the “Top of Bearing” label is up. Position the two holes marked with an Arrow so they are centered across the centerline of the plywood, drawn in Step 1. Keeping everything aligned, slide the bearing to within 1/8” of the plywood’s edge (4). Use the pencil to write “Bottom Plate” on the plywood offset from the center of the opening.
I’ve added two more Arrows to the bearing of Step 3. Use the pencil to trace the four holes marked with Arrows, onto the plywood (5).
Trace a line, with the pencil, around the outside of the bearing onto the plywood. Angle the pencil slightly inward and keep the same angle as you trace (6).
The larger hole near the perimeter of the bearing is the access hole. Trace the outline of the access hole with the pencil (7).
Set the bearing to the side and use a sharp nail with a hammer to mark the center of each of the traced mounting holes. Then use the yard stick and pencil to draw a line between the two mounting holes without a centerline between them (8). The two intersecting lines mark the center of the bottom plate.
Use a new envelope as a right angle (90°) and draw a line from the two marked holes with the new centerline (Step 7). Use the yard stick to measure 1-3/8” from each hole and mark these two locations with a pencil (9).
Draw a line between the two 1 3/8” marks of Step 8. Then measure 2 3/8” from the original centerline of Step 1, both above and below the original centerline and mark these two locations, on the 1 3/8” line (10).
Using the yard stick carefully pencil two lines radiating from the center of the Bottom Plate, through the two marks of Step 9 and continue the lines past the perimeter trace of the bottom plate (11). Note that this creates three 120-degree angles between the two lines and the original centerline. These angled lines will be used to mount the turntable’s legs.
Measure 1 7/8” from center of the Bottom Plate, up each 120-degree line and make a pencil mark. Use the hammer and nail to mark each location (12). These are the future locations of the inside ¼” bolts which will secure the aluminum legs.
I used a vitamin bottle cap that was 2” in diameter to create a circle for the future center cut-out. I centered the cap by measuring the radius of the cap, 1” up each 120-degree line and marking the location with a pencil. Then I centered the cap using the pencil marks and drew a line around it (13). Don’t make the circle larger than 2” or the structural integrity of the leg mounting bolts (at 1 7/8” marks) can be compromised.
Lay the turntable bearing so the side marked “Bottom of Bearing” is up. Rotate the bearing to line up the Access Hole with the large mounting hole on the opposite side of the bearing. Now look inside the two holes marked with Arrows. They should have a corresponding smaller mounting hole on the back of the bearing aligned with them. You can lift and rotate the bearing over to see that the mounting holes are marked with asterisks on the “Top of Bearing”, match the two arrow marked holes on the “Bottom of Bearing”.
Position the two arrowed mounting holes across the original centerline with the edge of the bearing on the edge of the Plywood. Don’t worry that the bearing overlaps the “Bottom Plate” plywood outline trace (14).
I’ve marked the two remaining mounting holes on this side with a couple of Arrows. Use a pencil to trace the outline of all four mounting holes (15).
Lay the bearing to the side and mark each mounting hole’s center with the hammer and nail. Use the yard stick to pencil a line between the two holes without a centerline between them and mark the crossing of the two centerlines with the nail and hammer (16).
Use a piece of Cardboard or in my case a piece of 94-pound paper and draw a line across it. Using the yard stick and a very sharp pencil, make two marks on the line 5.75” apart (17).
Cut away excess paper around the line and marks, creating a swath about 1” across. Then use the sharp nail or Awl to barely penetrate both of the marks (18).
Position one marked paper hole over the intersection of the two cross centerlines of Step 15, then gently push the nail or awl straight down into the crossed centerlines about ¼”. Using a very sharp pencil placed in the remaining hole, gently rotate the paper or cardboard around the nail, tracing a 5.75” radius cut line (19). Remove the nail / awl and paper.
It’s time to fire-up the jig saw. Cut out the plates and access holes. Note: The jig saw blade is slightly wider than the pencil lines of the two plate’s perimeter cut lines. For this reason, keep the jig saw blade just to the outside of the pencil lines. We will sneak up on the pencil lines with a sanding block and coarse sand paper.
The “Bottom Plate” has both the 2” center hole and the 1” access hole that need to be cut out. If you don’t have hole saws or paddle bits for the drill, simply drill a ½” hole inside both the traced cut out holes and insert the jig saw to cut them out. The 1” access hole can be larger. I cut mine at 1 ½”.
For clarity, I’ve noted the two cut-out lines and the two cut-outs (20).
Note: Before starting this Instructable I had already cut and drilled the two turntable plates, so I’m going to switch to them now and save my layout illustration piece of plywood for another project.
Once the plates are cut out, use coarse sand paper and a sanding block to clean up the perimeter cuts with some hand sanding. Make all the peaks match the valleys while creating a smooth circular edge. Start with short strokes focused on the peaks while rotating each plate. Then do long strokes to create an even gentle curve. While sanding, do your best to keep the sanding block perpendicular to the edge of the plate.
Caution: Don’t sand into the penciled perimeter cut lines (especially with the “Top Plate”). Let the outside pencil edge be the smooth circular boundary (21).
Spray the edge of each plate with grey primer (22).
If you don’t have a staple gun use some spray adhesive and glue a coarse piece of sand paper to a smooth flat face on a 1” x 4” x 18” board (23). Use five 2 ½” deck screws and attach the sand paper board to the end of your work table. The board needs to be screwed tight so it is at a 90-degree angle perpendicular to the work table’s surface (24).
Lay the “Bottom Plate” on top of the work table and slide the edge of the plate down the length of the sanding board while rotating the Plate. This will make the Plate’s edge perpendicular to the Plate’s surface. Flip the plate over a few times while sanding, just in case the sanding board’s not exactly perpendicular. When all of the primer is sanded off you will know that all irregularities have been removed and the plate is ready to be mounted (25).
Drill a 1/8” hole through the center of the “Top Plate”. Turn the plate over so the smooth “B” side is on top. Use a ½” paddle bit to drill completely through the plate, using the 1/8” hole as a guide.
If you don’t have a paddle bit, use a pencil and the shank of a regular ½” drill bit and draw a ½” diameter circle, centered around the 1/8” pilot hole. Use a razor knife to cut out the ½” circle. Cut down to a depth of the top veneer. Now you can use the regular ½” drill bit to drill the hole without severely splintering the plywood’s veneer (26).
Use the tailor’s tape and measure the circumference of the “Top Plate”. My circumference was 36 7/16“(27). Place the ½” x 4 ½” bolt in the center hole of the Plate, to use as a hand grip and sand down the edge (28).
Rotate and sand until the edge is perpendicular and the circumference of the “Top Plate” is exactly 36”. Then remove the bolt hand grip.
Caution: measure the circumference frequently so you don’t go below 36” of circumference. 7/16” of extra circumference equals a little more than 1/16” (0.0625”) of radius.
7/16” (0.4375”) / pi (3.1416) / 2 = 0.0696” of radius.
Note: This step took a lot of sanding but the result was worth it. I switched back and forth between using my sanding block to remove a lot of material and the sanding board to reestablish my perpendicular edge.
Use a razor knife to cut the tailor’s tape at the ½” mark and the 36 ½” mark. Wrap the top of tape around the Top Plate one more time to make sure the two ends touch. If they touch, spray contact adhesive onto the edge of the “Top Plate” and the back of the tailor’s tape. I sprayed the Top Plate upside down so the bearing side of the plate would receive the over-spray adhesive.
Caution: When applying the tape to the plate, make sure the “Top” face of the Top Plate is up, have the plate on a flat surface and wrap the tape (numbers up) around the Plate using the flat surface to guide the bottom edge of the tape.
After letting adhesive dry slightly but while still tacky, position and adhere the tailor’s tape around the edge of the plate. (29).
Use the yard stick, masking tape and pencil to mark both ends of each 16” aluminum leg. Place the two marks centered along the length of the leg, ½” from each end of the square tube (30).
Drill a ¼” hole through only one face, at one mark, on one end of each square tube. At the remaining mark, on each square tube, Drill a 0.332” (Q bit size) or 0.3281” (21/64” bit size) hole completely through the square tube (31).
Insert a ¼”–20 aluminum rivet nut into the “Q” hole face of each tube that doesn’t have a ¼” hole in the opposite end of the tube on the same face (32). Seat the rivet nut with a hammer.
Place each piece of tubing into a vice to set it's rivet. Thread a ¼”–20 x 1 ½” hex bolt into a ¼”–20 hex nut and then screw the nut and bolt into the river nut. Use two 7/16” wrenches to seat the rivet nut (33). Then remove the bolt, nut and the tubing from the vise. Repeat the process for the other two aluminum legs.
Using a carpenter’s square and a pencil continue the 120-degree lines created in step 10 over the edge of the “Bottom Plate” (34).
Use four #8 x 5/8” Phillips Pan Head Sheet Metal Screws and a #2 Phillips Screw driver to attach the Turn Table Bearing to the Bottom Plate, at the locations marked in Step 7 (35). Note: Make sure you match the Access Hole locations of the Bottom Plate and Bearing.
Drill three ¼” holes through the Bottom Plate, at the leg bolt locations marked in Step 11 (36).
Insert three ¼”-20 x 1½” Hex Head Bolts through the Bottom Plate ¼” holes and into the ¼” holes of the three, square tubing legs. Temporarily, secure them with ¼”–20 Hex Nuts only.
Position the assembly with the legs down, on top of the work table and align the 120-degree edge marks made in Step 31 with the centers of the square tubes (37).
Place masking tape on the inside of the bearing above the radiating 120-degree lines. Use a narrow putty knife as a straight edge and mark the three lines on the tape. With the yard stick, measure ½” up each line, from the inside of the bearing and make a pencil mark (38).
Double check that the square tubes are still centered on the edge lines. At the marks made in the last step, use a ¼” Drill Bit and drill through the bearing plate, the Bottom Plate and the square tubes (39).
Remove the three ¼” hex bolts installed in Step 34. Re-install them into the ¼” holes drilled in Step 37, but this time use a ¼” lock washer inside each square tube to keep the hex nut tight. Small fingers and patience are a plus when getting the washers and nuts on the bolts, inside the tube. I was able to do it despite my big fingers and lack of patience. When you tighten the nut, wedge a large flat tip screw driver between the nut and the inside wall of the tube, to keep the nut from spinning.
Repeat Step 34 using new nuts and bolts along with flat washers under the bolts and lock washers under the nuts.
Position the “Top Plate” upside down on the work table. Rotate the bearing so one of the Top Plate mounting holes is centered in the Access Hole of the Bottom Plate. Refer to photos 40 and 41 for clarification. Position and align the Bearing Top Plate mounting hole (in the Access Hole) to a mounting hole in the Top Plate.
Use four #8 x 5/8” Phillips Pan Head, Sheet Metal Screws and a #2 Phillips screw driver to attach the Turn Table Bearing to the Top Plate, through the access hole, at the locations marked in Step 15 (42). Note: Don’t tighten the screws completely until all four are inserted in the Top Plate. Just screw them in enough so the bearing’s access hole can be rotated to the next screw location.
Use a couple of wrenches to tighten the ½” coupling nut snug against a ½” hex nut, on the ½” all-thread. Then thread the ½” self-locking, nylon insert hex nut onto the opposite end of the all-thread, until 1/8” thread protrudes (43). Loosen and remove the hex nut and coupling nut.
Place the ½” ID x 1/8” thick fender washer on the all-thread (44) and thread it through the Top Plate, from beneath the assembly.
Place a ½” washer onto the all-thread and then wrap masking tape around the all-thread, just above the washer and 9” above the washer. Wrap the tape at both locations until it’s thick enough to act as bushings to keep the PVC centered around the all-thread (45).
Place the PVC over the tape bushings, add the ½” washer, ½” lock washer and ½” coupling. Tighten the assembly using two wrenches (46). Sand the surfaces of the ½” washers, ½” lock washer, ½” coupling nut and PVC Tube.
Mask the adhered tailor’s tape with masking tape and trim of the excess tape with a razor knife.
Sand and clean the assembly, install a ½” bolt in the top of the coupling (no spray on threads), then coat it thoroughly with spray primer / paint (47).
After drying, remove the masking tape and thread cover bolt, from the assembly. Then attach the self-adhesive rubber feet to the bottom of the aluminum legs (48).
Note: The round PVC cap is normally not secured to the base plate. The three aluminum legs keep it confined during application of heavy loads (49). Normally it’s treated as a loose accessory. If you decide to attach it, I would suggest using double sided tape applied to the deck plate and cap edge. This will give you easy access to the column nut if you ever need it.
The base assembly can be adjusted to what you want to model. Here we see the removable cap pivot, rubber feet and adjustable bolt feet (50).
If your modeling is confined to smaller subjects, you might decide not to install turntable legs and just use rubber feet attached directly to the lower deck.
If you are prone to modeling large bulky models with an off center, CG (center of gravity), weighing less than 20 lbs, the legs and bolt feet will do nicely.
There is a variety of choices for the discriminating photogramist.
Specialized model mounting hardware flexibility is accomplished with the ½”-13 transition coupling. To kick start your creativity, I’ve included a few securing devices that I will use soon.
The first is a spike, made from an old screwdriver nested in a hole drilled into the head of a ½”-13 bolt (51).
Second is a glob of hot glue seated on a ½”-13 carriage bolt (52). I call it the “Glubber”. Heat the glue to re-use it on the base of models.
Next is the offset plate. Very handy for keeping the model centered during rotation while utilizing a screw hole in the base of the model (53).
My last example is a carriage bolt wrapped with masking tape to support a model that can be clamped around it (54).
I hope that this Instructable has inspired your creativity and that you will share your re-mix of this project.
Neither mesh is pristine, but I credit myself with that achievement.
I should have illuminated the white sheet of Formica backdrop with another diffused light source, or switched to a darker backdrop to contrast more with the primer color sprayed on the two test subjects.
I’m a Noob :) But I’m learning.
The photos were taken with the following settings:
exp. time 1/40 sec.,
Auto-focus off, manual focus unchanged during shoot.
I used a string tied to top of support column to maintain same lens distance from subject, when I changed the camera's elevated position (twice).
Participated in the
Build a Tool Contest