Case Study - Chair Step Ladder

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Chair Step Ladder AnimationDale Hellewell is a hobbyist CNC woodworker who has been using Vectric software for the last four years. All the things Dale makes are for his own use or given as gifts to family, friends or to raise money for good causes. Despite his desire not to sell things commercially Dale still produces high quality and imaginitive products with his CNC. Recently Dale posted files for a Chair/Step Ladder Project on the Vectric Forum that was downloaded over 300 times.

We were lucky enough to meet Dale at our 2011 User Group and recently caught up with him to ask him more about his work with Vectric software. As an unexpected bonus he also provided us with more information on assembly for his chair/step ladder design and tips and tricks to get the best results.

Dale started by explaining how his woodworking hobby morphed into incorporating CNC technology.

"I started working with my own CNC when I was contacted by Legacy Woodworking in the spring of 2007. Legacy's idea was to convert my Legacy 1200 and beta test it as a CNC machine. I was already familiar with CNC used to manufacture metal siding and floor deck. First encountering it as early as 1971, the primary purpose in those days was simple; to count the number of sheets, punch holes and cut them to length. In the years that followed CNC didn't change much until the last decade when affordable software and computers have made it accessible. I wrote code for my own CNC projects in GCode using a spreadsheet to lay out the coordinates for games like Chinese checkers, aggravation and marble checkers. These games also incorporated a groove for marble storage cut using a turntable and are designed to hang on the wall. "

In 2008, Dale got involved with testing Vectric's VCarve Pro software on his Legacy 1200 Performance Series CNC machine. Since then he has created a wide variety of projects including signs, games, toys, carvings, canes, walking sticks, wrapped carvings and more. He regularly posts his results on the Vectric forum under the username dhellew2. It wasn't long before Dale decided that he would like to upgrade to Aspire and here goes on to explain that his choice has not only enhanced his hobby, but others as well.

"Aspire has opened up the world to endless possibilities, limited only by the imagination of my wife of 40+ years. I rarely work on less than a dozen projects at one time and have enjoyed making more advanced projects since upgrading to Aspire. Something I'm currently trying to perfect is a blanket holder with carved ends, the plan here is to carve one side then flip it over, using guide pins, then carving the same but reversed image on the other side. This is just an example of one of the many ideas I'm currently working on."

Toy Cars Wall Art Lithophane Dish

"In 2008 my farmer neighbors approached me after noticing my work, they wanted to learn more about woodworking as they were interested in taking it up as a retirement hobby. Like most woodworkers I enjoy teaching other people and their Lawrence Vineyard Gard wine and apples that I received as gifts have been an unexpected bonus."

Since their interest in CNC, Dale has mentored his neighbors for three years as they continue to develop their woodworking hobby. During Christmas 2010 he was asked by them if he could demonstrate how to build a chair/step ladder. The timing of the project was ideal as it provided a good reason to upgrade his CNC to the new welded design Artisan frame and provide Legacy with feedback on its performance. The concept of a combined chair and step ladder is one that Dale remembered seeing in an old catalog and with a bit of research he was able to develop his own design. The final version was a customizable chair/step ladder that would be fit for any home. Dale concluded our brief interview by giving us an overview of the process and this is followed by the project files and his instructions for making your own version of the design.

"When I started the project I got my dimensional guides from an old oak chair and a step ladder. I then created the project in TurboCad so I could rotate the ladder to verify it's fit, stability, and aesthetics.

Finish Chair Step LaddersAspire was then used to create the finishing touches on the project and to generate the toolpaths. The first four chair/step ladders I finished were very well received at Christmas, so leading into Christmas 2011 we produced six more chairs and received requests for six more, including orders from my wife and daughter!

Ten of the completed chairs are northern red oak and two are black walnut. All the chairs are finished with Circa 1850 Teak/Tung Oil from Jamestown distributing."

We would like to thank Dale for taking the time to talk with us and for being generous enough to share his design with fellow Vectric users. To see Dale's work and to keep up with his new projects Click Here to join the Vectric Forum today and look out for user dhellew2! Below you will find the links for the files to cut Dale's chair/step ladder and his instructions for assembly.


Project:

Click here to access the download project filesTo access the project files you need, please visit Dale's post on the Vectric Forum where they are available for download. Click the button to the right to view the forum post which also includes modified versions submitted by other forum members.

Disclaimer: This project is provided as a guide to producing Dale's design. You should carefully check all aspects of this before running it on your own equipment, to ensure that the layout, tooling, toolpath parameters and format are suitable for the material you plan to use and your CNC setup. You should be 100% sure that all the settings are compatible and safe for use with your CNC before proceeding. Vectric Ltd. and Dale Hellewell accept no liability for the following chair/step ladder project files and instructions or for the consequences of any actions taken on the basis of the information provided.

 

Material List
Materials
Qty Description Size
1 Chair/ladder right and left sides * 0.8"** x 12.5" x 36"
1 Chair bottom right and left sides 0.8 x 16" x 36"
1 Chair back and stretcher 0.8" x 16" x16"
1 Chair /ladder end cap ¾" x 2.875" x 16"
1 Chair bottom step ¾" x x 14.375"
1 Chair/ladder step ¾" x x 14.375"
1 Seat front ¾" x 7.25" x 17.5"
1 Seat back ¾" x 7.5" x 17.5"
1 Piano hinge with screws 1-1/2" x 16"
18 Pocket screws #8 x 1-1/4"
6 Figure-8 brackets  
6 Flat head screws for figure-8 brackets #8 x 1-1/4"
6 Flat head screws for figure 8-brackets #8 x 5/8"
4 Deck screws for chair/ladder end cap #8 or #9 x 1-1/2"
6 Pocket screw plugs 3/8"
4 Face plugs 3/8"
  Wood glue  

Guidelines & Tips:

  • Material thickness can be 0.75" and thicker; I use 0.82" which will work with ½" dowels and 0.125" deep v-carving. For ¾" wood with v-carving I recommend using 3/8" diameter dowels.

  • To save material cut one side of the chair/ladder side then flip the board lengthwise and cut the other side.

  • To match the shape of the chair, the seat and steps can be cut faster and easier with a ilting arbor table saw.

  • Sand all the parts and round all the edges before assembly (except where the steps insert into dados,the top of the chair where seat sits, and the chair/ladder end cap)

  • I learned that 4-flute bits don't work in hardwood, they burn, use 3-flute spiral bits; best cut results angled across the grain is with 0.05" diameter 3-flute spiral bit.

  • Cut test holes first to make certain the dowels will fit.

  • Make cleanup cuts on dados (duplicate tool path).

  • NOTE: It is not necessary to use a piano hinge. Use the hinge(s) of your choice as long as the chair/ladder functions properly. When in the ladder position you don't want your weight supported by the hinge screws, so ensure there is a zero gap between the front and back seats when folded up.

 

Assembling the Chair

HingesBracket

The chair assembly is facilitated with the use of a piano hinge, pocket screws and figure-8 table brackets. No glue is required at this stage, but if you must glue use a non-hardening construction adhesive and screws. Wood glue will not glue end grain.

When attaching the figure-8 bracket ensure the holes are 1/8" deep, both holes need to be cut in the bottom of the seats with two Forstner bits to match the size of the figure-8 brackets.

Firstly fasten the figure-8 bracket to the chair with #8 x 1-1/8" screws and then to the seats with #8 x 5/8" screws. There are two figure-8 brackets in the front seat positioned approximately 1" from the back edge, plus two pocket screws in the stretcher. The back seat has 4-each figure-8 brackets placed approximately 1" from the front and back edges.

BracketPocket Screws

Pocket screw holes and screw holes that are exposed in the ladder position are plugged. I make my own dowels with a Veritas dowel maker then cut them to shape with a band saw.

To finish, be sure to round all exposed edges with a 1/8"roundover bit and cut all the way around the leg bottoms to prevent tear out and scratching of the floor. Finally round both sides of the handle hole.

Important: Don't round the sides of the back where the dowel go or the top edge where the seat goes.

 

 

Creating the Dowels

Dowels 1MeasuringDowels 2

When creating the dowels I use a machinist angle which is clamped to my drill press table. This also aligns the holes front to back in a straight line making it much easier to align the holes.

Tips:

  • Make certain your dowel holes do not cut into your v-carving.

  • When measuring always use the same tape and always measure from the same starting place. With dowels there is no room for accumulative or subtractive measuring errors that always happen when measuring from hole to hole.

  • When gluing you will find that torn strips of paper towel strips suck-up glue without smearing. Plastic drinking straws scoop up (or suck-up) glue in corner joints. Put strips of cotton rags in water with a little lemon dish soap, wring tightly and wipe up excess glue (the soap helps remove the glue without harming the finish to be applied later. Round tooth picks also work great when gluing holes.

Drilling Straight Hole:
To drill an effective and straight hole use a Forstner or brad point bit.

Dowel Hole Location:
Draw a line at the hole center parallel to the back edge. Insert the pins into the holes in the chair/ladder sides, now align the first and last pin on the line scribed on the back. Alternatively you could use an Incra stainless rule that uses a 5mm pencil. After using a 5mm pencil it is a good idea to use a sharp center punch or ice pick to mark the exact center spot before drilling. When using dowels the holes typically must be within 1/64th inch of center.

Dry Assemble the Back
Verify that the dowels are not too long (leave a ¼" or so for excess glue) then glue the dowels to the chair sides first. Whilst the glue is still wet glue the holes in the back and push the back onto the dowels. Repeat this for the other chair/ladder side.

 

Installing the Hinge

NOTE: To prevent the end of the screws from poking out it may be necessary to drill at a slight angle towards the center of the boards.

Tips:

  • NEVER USE BRASS SCREWS on a chair or a ladder. Use yellow zinc plated or brass plated steel screws to prevent screw failure under load. It may be necessary to counter sink the holes in the hinge if the screw heads stick out too much. You only have 1/32" clearance for the screw head when the seat is in the chair position.

  • Most screws have a single thread which can cause the screw to push to one side of the pilot hole. To prevent misalignment push the screw into the pilot hole hard to force the screw shank to the center of the pilot hole. Hold the screw down tightly until the screw thread is started. Once you tighten a few screws in strategic places you can lift up the hinge enough to remove the double sided tape without losing alignment.

Firstly align the two seat halves face to face and clamp them loosely. Mark the ends of the hinge location and slip a small piece of paper up to the hinge line on each end then finish clamping them together.

Hinge 1Hinge 2Dish

Next put 3 short pieces of double-sided carpet tape on each half of the seat within the hinge area. Align the hinge with the pin centered on the edge of the paper and press onto the double-sided tape. The hinge pin must be centered in line with the faces of the seat.

Hinge 4Hinge 5Hinge 6

Test the seat before adding screws to verify its alignment. When the seat is opened it must be flat, when closed the two faces should be in contact with each other. Use a vix or snappy self centering bit to center and drill pilot screw holes.

 


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