I knew this was going to happen; When I first got the wood shell for my Sega Star Trek Captain’s Chair – Someone had already ripped several of the Leg Leveler T-Nuts from the wooden bottom. I figured – hey; can’t be a real problem so I epoxied in some new T-Nuts and went off to Texas Pinball Fest ’12 . Needless to say; three of the T-nuts didn’t make it back to Austin. Call it carelessness; or whatever, but I had to fix this.
When I first saw the original t-nut design; I thought it was stupid. The tnuts won’t hold… and neither will those two massive staples the put over the Tnut. If the nut can be pulled; so will the staples. Besides; it’s not like the sell those big staple guns at Harbor Freight or any home improvement store.
I whipped out Corel Draw and laid out some simple plates to “improve” the design. My goal is to make the t-nuts resistant to torque forces while keep the plates simple. Here’s my solution to help keep the T-nuts in place.
I have decided to release this design under to the public under the TAPR Non-Commercial Open Hardware License which indicates:
You may make products based upon this design, provided you do not make more than ten [sets] in any twelve month period for your personal use.
- 3x3x0.25 inch poplar sheet
- 5minute epoxy
- white Gorilla Glue
- 1/4″ Crown Staples (18 gauge, 1″ long)
- 3/8″-16 T-Nut (McMaster Carr #90975A031 )
The first three items were sourced from Lowes – but nearly any home improvement store should carry these items. The Staples were sourced from Harbor Freight for a previous restoration project. The T-nuts from Mcmaster Carr for the original Sega Star Trek restoration.
The design I came up with is as follows:
I cut the poplar sheet to fit to 24″ length so it would fit on my Laser table. Ran the Laser cutter at 50% power, 1.6 speed, 250 pulses per inch (ppi) to cut on the red lines. The Etches were vector engraved at 40%, 10 speed, 500ppi. Was it necessary to laser cut – heck no, but if you have the equipment; why not use it? Took two passes to cut through the 1/4″ poplar at these power levels.
You can download a full package ZIP file from:
Leg Leveler Plate Package
which contains the Corel Draw file and measurements in PDF form.
After Laser cutting; I had these nice plates. Since the wood on the bottom of my Chair was fairly beaten up in a couple of cases; I needed to secure the TNuts with more than just a hammer. I mixed the 5 minute Epoxy per directions at 50/50 ratio and coated the inside of prongs with the epoxy; then hammered in place. I coated the nut with more epoxy in an attempt to secure it better to the wood. Here’s an example of what I did to a friends dedicated Upright Star Trek machine which had simular issues:
In this picture; some wood filler was used to help secure some missing wood from where the tnuts were ripped out. Be sure not get any epoxy in the threads of the tnut… one way to do this is to run a old leg lever into the hole while the epoxy is setting.
The epoxy sets in 5minutes; but takes a minimum of 1hr to reach some strength; so I let the epoxied Tnut set for an hour and played some Star Trek Pinball.
The plate will be installed with the arrow facing the outside edge of the machine. For the Captain Chair; the orientation of the arrow doesn’t matter as the tnuts are far enough inside the machine to not matter. For the Dedicated upright machines; the Arrow side is 0.1inch shorter; so it will not overhang the front of your machine.
After the hour; I dampened the base of the machine and the plate with some water per directions on the Gorilla Glue packaging. I used the White version; because it cures in about 30-60minutes. I put a spiral pattern on the wood plate and stapled it in place with the 1/4″ crown staples. The Staples provide the clamping pressure while the glue sets.
For the first 5 or so minutes; watch the foaming action. Clean up any over spill of the foam – particularly in the hole near the tnut. After about 5minutes the foaming should stop and you run that same used/scrape leg lever into the threads to keep the hole accessible for your new leg bolt when completed. I used a large blade of the screw driver to scoop out the foam. I put about about 4 staples in an X pattern outside the 1 inch etch hole; which represents the metal Tnut which you don’t want to try to drive a staple into.
I put about 10-15 staples in the plate after initial orientation check – these staples may seem excessive; but I want to secure the wood plate to the bottom of the machine and provide a good even clamping pressure for the gorilla glue to dry. As the package says “Strength of the bond line improves with better clamping.”
Wait about 1hr for the gorilla glue to strength… At this point you can gently set the machine back on it’s legs. If you can wait at least 24hrs before any excessive moves – this will allow both the epoxy and the gorilla glue to reach full strength.
Oh; and don’t forget your new leg levers:
This plate should be nearly in-destructible; which could prove a problem if the tnut ever needs to be removed. Not sure why that would need to happen – comments / suggestions?