Let your imagination run wild

US stock · technic parts and 1:87 rail

We are ASTEM — we keep the bench stocked, from technic gears to HO scale rails

Two lines live on this bench. One is loose technic parts — gears, axles, pins, beams, motors — for people who build their own machines. The other is 1:87 railroading: locomotives, rolling stock and nickel silver track. Both are made by us, and both are here because a half-finished model is nobody's idea of a good evening.

What we make, and why it is sorted this way

We started ASTEM because the part you actually need is never the part in the box. A gear train jams for want of one 16 tooth cog. A chassis sits unfinished because four cross axles went missing in a carpet two years ago. So we built a parts library instead of another sealed set: deep packs of technic parts, graded by what they do rather than by what picture is on the front.

Every pack here is moulded in tough ABS plastic to the dimensions the technic system has used for decades, so a pin that should push home with a firm click does exactly that, and an axle that should spin free spins free. Compatible is a word that gets thrown around; we take it to mean our parts sit in your existing models without shaving, forcing or glue.

The second half of the bench is the railway. Our HO scale locomotives run on 12 V or 14 V DC, our freight cars roll on metal or copper wheels, and our nickel silver rail snaps together without solder. It is the same engineering habit applied to a different gauge — the fit has to be right or the whole thing derails.

Shelves on the bench

Ten shelves, sixty-nine packs and models. Start with the one that matches the job in front of you.

  • Gears and AxlesGears and Axles6 packsToothed drive parts: spur gears, worm sets, racks, differentials and the cross axles that carry them.
  • Bulk Parts PacksBulk Parts Packs8 packsDeep mixed packs for people who build every weekend and keep running out of the same four pieces.
  • Motors and PowerMotors and Power6 packsPower function motors, pull-back drives and engine kits that put a build in motion.
  • PneumaticsPneumatics3 packsCylinders, pumps, switches and hose for arms, grabs and tipping beds that move on air.
  • Light-Up BricksLight-Up Bricks5 packsTransparent studded bricks with a lamp inside, in warm, cool and mixed colour packs.
  • Wheels and JointsWheels and Joints3 packsRolling stock for models: moulded wheels plus steel ball and socket joints for steering linkages.
  • Display ModelsDisplay Models3 packsFinished large builds meant to stay assembled on a shelf rather than be taken apart for parts.
  • HO LocomotivesHO Locomotives8 packsPowered 1:87 switchers and road units with metal or copper wheels and CNC chassis.
  • HO Rolling StockHO Rolling Stock15 packsBoxcars, tankers, gondolas, flatcars and cabooses to run behind the locomotive.
  • Track and SceneryTrack and Scenery12 packsNickel silver rail, curves, turnouts and ground cover for the layout the trains run on.

If you are looking for a place to start

  • New to technic parts

    A mixed pack of gears and axles teaches you more in one evening than any guide. Build a two stage reduction, feel where it binds, and you will understand the system.

  • Rebuilding an EV3 or a classroom kit

    Go straight to the bulk parts packs. They are drawn from the same regular-sized mechanical parts those kits use, so replacements drop in without a second thought.

  • Laying your first layout

    Buy the track before the train. An oval of nickel silver rail with one turnout will tell you how much room you really have.

Most asked for on the bench

How we check a part before it ships

Every production run gets pulled apart on this bench. We push pins into brand-new bricks and into bricks that have been built with for years, because friction that feels right in a factory sample can feel wrong in a model that has been rebuilt twenty times. We spin gears under load, we check axle ends for flash, and we run locomotives for an hour on a test oval before a batch leaves.

That is the whole of our quality story: measure, push, listen, repeat. It is not glamorous, but it is the reason a true technic fit matters more to us than a glossy box.

Technic gears, axles and HO scale stock: what the ASTEM collection covers

A technic gear is a small part with a large job. The ASTEM collection starts with the toothed pieces — 8, 16, 24 and 40 tooth spur gears, worm screws, crown gears, racks and differentials — and the cross axles they ride on. Each building set in this half of the bench is LEGO® compatible in the only sense that matters on a workbench: the module, the axle cross section and the pin diameter match what you already own, so a technic gear out of our bag meshes with the gear out of your bin without reaming or filing.

Around the gears sit the parts that make a drivetrain into a machine. Motors in M, L and XL sizes, pull-back drives, pneumatic cylinders and pumps, light-up bricks, moulded wheels and ball joints for steering. Builders working on a crane, a gearbox or a rock crawler tend to order across two or three drawers at once, which is why every drawer page lists what sits next to it.

The other half is 1:87. HO locomotives with CNC machined chassis and metal wheels, boxcars and tankers and cabooses to run behind them, nickel silver rail in curves, straights and turnouts, plus ground cover for the scenery. The two halves share a bench because they share a customer: the person who likes a mechanism and wants to understand how it works before it is finished.

Every set we pack goes through the same checks — tooth profile on a sample gauge, pin friction in old and new bricks, wheel gauge on a test length of track. The experience we are aiming for is dull in the best way: you open the bag, the parts fit, and nothing about the hardware gets in the way of what you were trying to build.

What builders tell us

Six comments left by people who bought from the store, quoted as written.

  • 5.0 ★

    Great clutch, tight tolerances, and an excellent assortment of mechanical parts

    A very solid parts pack for custom mechanical and robotics builds. The gears, axles, differentials, and steering components mesh smoothly without slop or binding. Clutch power matches standard Technic pieces seamlessly, and the molding has no flashing or rough edges. Having a dedicated kit loaded with worm gears, cams, and linkage hardware makes prototyping drivetrains and motorized assemblies so much easier without cannibalizing other sets. Excellent value for MOC projects.

    Fibernick · October 18, 2026

    233-Piece Axle, Pin and Steering Parts Set

  • 5.0 ★

    Great start to inventory of pins. Very well packaged

    A nice variety of pins. I don’t think there were duplicate pins but I didn’t keep track. A great start for those just getting into Technic builds. Very well packaged in the most durable package I can ever remember receiving Suggestion for those new to Technic: buy a few of the multi item packages to build what will become a large number of parts. Then buy specific pieces from Bricklink or other similar sites.

    Frank · October 23, 2025

    6500-Piece Shaft, Pin and Bolt Assortment

  • 5.0 ★

    Great Product

    Bought this for my son who loves to build robots and animatronics. This was perfect for a beginning builder.

    Tracy · May 1, 2024

    33-Piece Pneumatic Cylinder and Pump Kit

  • 5.0 ★

    These are great!

    I’ll be buying more of these for sure, the only downside is I don’t have a use for some colors and I wish I could just buy more of the plain white ones!

    Eric fernandes · December 8, 2023

    2x2 Light-Up Bricks, Mixed Colours, 12 Pieces

  • 5.0 ★

    Nice tires

    My son picked these out to use on his huge remote control vehicle he builds each year for a lego competition. He says they look great, feel great and work awesome. Definitely wants to get another set for the price. Great value.

    Jamie Treinen · January 15, 2025

    4-Piece Wheel Set, 15038 and 23798 Pattern

  • 5.0 ★

    Excellent value

    Great value for 3rd party LEGO parts, some of the peghole connectors can feel pretty stiff but everything fits.

    Jon Charron · December 2, 2025

    270-Piece Gear, Differential and Rack Set

Questions people ask us

What are ASTEM technic parts made of?

Tough injection-moulded ABS, the same family of plastic the technic system has always used. It takes a clutch load without creeping and it does not go brittle in a cold garage.

Will these parts fit the sets I already own?

Yes. Pins, axles, beams and gears are moulded to standard technic dimensions, so they fit alongside LEGO® Technic and other compatible building blocks without modification.

How many pieces come in a pack?

It depends on the shelf. Gear packs run from fifty-odd pieces to several hundred; the deep assortments go to several thousand. The count is in the name of every pack on this site.

Are these suitable for a beginner?

The parts packs are, and so are the small gear sets. The large display models and the powered locomotives assume you have built something before.

Can I use them for school or robotics projects?

That is what the EV3 replacement groups exist for. Teachers buy them to keep a class set running when the original trays start to thin out.

Is any of this safe for small children?

Technic parts are small by nature. We mark our packs for ages eight and up, and we would keep axles and pins away from anyone who still puts things in their mouth.

How should I store a big assortment?

Shallow drawers beat deep tubs. Sort by function — gears with gears, pins with pins — not by colour, and you will stop losing an hour to looking for one piece.

What do I do if a pack arrives damaged?

Open an order problem in the partner store you bought it from and they will put it right; our swap counter page walks you through it.