Leveling Screws and Hardware Upgrade for JMI Wheeley Bars, Triangle Style for 8″, 10″ & 12″ Dobsonians

Product Overview

The JMI Triangle Style Leveling Screws and Hardware Upgrade kit adds 5/8″ leveling to a Triangle Style Wheeley Bar — the Dobsonian platform built for 8″, 10″ and 12″ scopes. Out of the box that platform rolls on its wheels alone; this kit supplies three 5/8″ × 10″ leveling screws together with the threaded inserts and fasteners that carry them on the Triangle Style frame. The inserts bolt to the frame’s existing mount points and the screws thread in from there. The complete kit weighs 5 lb and is made in the USA by JMI, part of the CXB Astro family.

Who It's For

This is a good match if you own a JMI Triangle Style Wheeley Bar and observe from a pad, driveway or field that is not dead level. A Dobsonian tracks by hand, so a rocker box sitting a degree or two out of level drifts faster in one direction than the other and you spend the session catching up. It also suits you if you already run the 5″ caster upgrade and want the rest of the ground game to match.

Key Features & Design

• Complete kit: three 5/8″ × 10″ leveling screws plus the threaded inserts and fasteners needed to carry them on the Triangle Style frame.
• 5/8″ heavy-duty thread: the current JMI HD diameter, which carries the platform load without flex and matches JMI’s 5/8″ accessory thread.
• Bolt-on installation: the inserts use the frame’s pre-drilled mount points, so the job takes 15–20 minutes with basic hand tools.
• Hand-turned knobs: a quick twist on each of the three screws levels the platform before a session.
• Kit weight: 5 lb.
• Made in the USA by JMI, part of the CXB Astro family.

Mechanical Design

A Dobsonian platform on casters alone has no way to take up a slope. The rocker box follows whatever angle the ground gives it, and because the scope is nudged by hand rather than driven by a motor, that angle shows up as an asymmetry in how the field drifts — faster one way, slower the other, and different again when you swing to another part of the sky. Three-point leveling is the standard answer because three points define a plane: with one screw per corner of the triangle, any ground angle within the screws’ travel can be taken out, and the platform cannot rock the way a four-point arrangement can.

The load path is what makes the 5/8″ diameter matter here. With the screws down, the full weight of the platform, the rocker box and the telescope sits on three slim threaded columns rather than on the wheels. A 5/8″ shaft in a threaded steel insert has substantially more section than a 1/2″ one, so it deflects less under a 12″ Dob and wears its threads more slowly over repeated setups. Bolting the inserts to the frame’s own mount points rather than tapping the frame itself keeps that load in hardware designed to carry it.

Recommended Uses

• Levelling a Triangle Style platform on a sloped driveway or a crowned asphalt pad.
• Setting up at a star party where the assigned patch of ground is whatever it happens to be.
• Taking the wobble out of a garage floor or observatory slab that drains to one side.
• Making manual tracking behave the same across the sky through a long session at high magnification.
• Pairing with the 5″ lockable caster upgrade so the platform both rolls and parks properly.

Compatibility and Accessory Notes

• Triangle Style only: the hardware is sized for the JMI Triangle Style Wheeley Bar for 8″, 10″ and 12″ Dobsonians, and fits the whole Triangle Style range.
• Thread standard: 5/8″, matching JMI’s current HD accessory thread. The JMI 5/8″ Speed Dial Drill Adapter therefore drives these screws with a cordless drill.
• Universal-style bars use a different frame and different mount points; their leveling screws are fitted at the factory and the 5/8″ or 1/2″ replacement sets cover those.
• Sky Trekker models fall outside this fitment.
• Pairs naturally with the 5″ Lockable Caster Wheels upgrade for the Triangle Style frame.

Tell us which Dobsonian and which Wheeley Bar you run and we’ll check the fit for you.

Good to Know Before You Order

• The Triangle Style bar ships without leveling screws. Levelling is an upgrade on that frame rather than standard equipment, which is what this kit adds.
• There is no 1/2″ version of this kit. Triangle Style leveling is 5/8″ only.
• Installation is a bolt-on job, not a bolt-free one. A basic hand-tool set and 15–20 minutes cover it the first time, and the instructions are in the box.
• Soft Ground Feet are specified for Universal-style bars. The 5/8″ thread itself matches, so if you want wider feet on a Triangle Style platform for soft ground, get in touch and we’ll check fitment with CXB Astro first.
• The kit weighs 5 lb and ships as one carton.

Frequently Asked Questions

Is it difficult to install?

No. The threaded inserts bolt to mount points the Triangle Style frame already has, and the leveling screws thread in by hand afterwards. Most first-time installs run 15–20 minutes with a basic hand-tool set, and there is no drilling or cutting.

What exactly is in the box?

Three 5/8″ × 10″ leveling screws, the threaded inserts that bolt to the frame, and the fasteners that hold the inserts. Once the inserts are on, the screws thread into them.

Why 5/8″ rather than 1/2″?

5/8″ is JMI’s current heavy-duty standard. The larger thread carries more load with less deflection under a heavy Dob, and it matches the 5/8″ accessories such as the Speed Dial Drill Adapter. No 1/2″ version of this kit exists.

Can the screws be driven with a drill?

Yes. The JMI 5/8″ Speed Dial Drill Adapter fits this thread and spins the screws up and down with a cordless drill, which cuts setup time noticeably when all three have a long way to travel.

Will this kit fit a Universal-style Wheeley Bar?

No — the frame and mount points differ. Universal-style bars come with leveling screws from the factory, and the 5/8″ and 1/2″ replacement sets serve those.

Bottom Line

In short: a USA-made 5 lb kit that puts three 5/8″ × 10″ leveling screws and their mounting hardware on a JMI Triangle Style Wheeley Bar, so an 8″, 10″ or 12″ Dobsonian platform can be levelled in seconds on ground that is not. Bolt-on in 15–20 minutes, and it pairs with the 5″ caster upgrade.