Automatic Screw Sorter

You know you want one!

If you have mountains of unsorted screws in your workshop, you probably spend lots of time looking for "just the right" screws for a job.

This screw sorter is the answer! It can sort all your different screws to length, for storage and easy access.

I found three designs on You-tube -

Video 1: Felix the handyman: https://www.youtube.com/watch?v=YA69V4txt-M

Video 2: DTU students project : https://www.youtube.com/watch?v=mnoKHHNhiiQ

Video 3: Ray's Screw sorting machine: https://www.youtube.com/watch?v=mnoKHHNhiiQ

I did a simple prototype of the DTU design, but screws with all threads and no smooth shank consistently jammed.

I developed my machine based on Felix's design.

I opted for 10 slots to sort a range of screws from 10mm to 62mm

I would have liked to sort screws smaller than 10mm but the head size (typically 7mm) prevents them from falling through the slot. This can even be a problem for screws up to 13mm, depending on the head size/design/screw gauge.

The spacing between the down-tubes determines the width of the collection boxes that catch the screws so this is best worked out at the design stage.

I used square aluminium tubes for the collection boxes, the same size as the down-tubes for consistency and ease of fitting but they are shallow and don't hold a lot of screws.

Step 1: Materials List:

Bottom baseboard 25 mm x 460 mm x 220 mm

Top baseboard 25 mm x 210 mm x 440 mm

2 x Uprights 38 x 90 x 219

1 x left hand front upright 38 x 68 x 226

1 x right hand front upright 38 x 68 x 224.5 (to accommodate a 1.5mm steel reinforcement plate)

The 68x38 mm & 90 x 38 mm wood is non-structural pine, bought very cheaply at Bunnings.

2 x Wooden battens 40 x 20 x 200

Motor board 15 mm x 185 mm high x 210 mm wide

2 x wooden spacers 80 x 85 x 20 to join the motor board to the fixed upright

200 watt ¼ sheet orbital sander

1 metre 25 x 25 mm Aluminium Angle

Square Aluminium tube 25 x 25 x 1800

Flat aluminium bar 2 mm x 30 mm x 1 metre.

4 x strong springs 30 x 15 mm (I got mine out of scrapped hot water overflow valves)

4 x medium springs 30 x 10mm

4 x 6 mm steel rod 210 mm long with 25mm M6 threads on each end

8 x 6 mm washers

8 x spring washers 6 mm ID 10 mm OD

6 x M6 Nyloc nuts

4 x M6 coach bolts 75mm long

4 x M6 threaded inserts

8 x 25mm countersunk woodscrews

4 x 75mm countersunk woodscrews

4 x 50mm countersunk woodscrews

1 roll of 50mm gaffer tape.

Plastic insulation tape

Inner tube rubber, foam, or other vibration damper.

Super glue

Contact cement

Step 2: Tools:

ESSENTIAL TOOLS:

tape Measure/Ruler

Set square

pencil/scriber/marking knife

Drill and bits

Screwdrivers

Wood saw

Hacksaw

Ball Pein Hammer or round wooden mallet

NON-ESSENTIAL (but very useful) TOOLS:

Drill Press
Band Saw

Table Saw

Drop saw/slide saw

Jigsaw

Hole saw

Pop riveter with 1/8” rivets

Router with 10mm flush trim cutter

Spot welder.

Mig welder

M6 Die and die stock (or use M6 all-thread)

M4 x 0.7 tap (self tapping screws can be used instead of threaded bolts)

Step 3: The Baseboards:

• Cut baseboards to size,
• Drill 7mm holes for the 75mm bolts that hold the boards together.
• The holes are 7mm (1mm larger than the bolts) for minimal contact & vibration transfer.
• Fix bolts to the bottom board with a nut.
• Put the vibration damping springs over the bolts. (My springs came from scrapped hot water heater overflow valves.)
• Screw the 50 x 50 cleat to the bottom board, but don't assemble the 2 boards at this stage, as there is some fitting & drilling to do on the top one. (see photos)

Step 4: Uprights and Fixed Guides:

• Cut the fixed uprights.

NOTE the 1.5 mm chamfer on the top of the fixed uprights where the flat aluminium guide sits. This is to help the screws fall through the slots into the down tubes. This was a later refinement in my build, and because it would have been a major job to do this chamfer once I had assembled the whole machine, I put a 1.5 mm plastic spacer under the back of the aluminium guide to give it some tilt, Its best to put this tilt into the design from the beginning. (see photo).

• Drill 7 mm holes through the uprights for the adjusting bolts 45 mm from the bottom of each upright separated by 70 mm on each upright – Use a drill press for accuracy and drill in to the centre from each side of each upright. NOTE: I originally had the bolts only 50 mm apart, and the levers on the adjustment nuts collided. Putting the bolts 70 mm apart prevents this, but the sorting plate had to be drilled (12.5mm )to give clearance for the spring
• Drill 8 mm holes to a depth of 12mm on the outside face of the fixed upright for the threaded inserts.
• Screw the 90 mm uprights to the baseboard with 75 mm screws.
• Put springs in between the fixed and the movable uprights to test clearances. I used 4 x 10 mm diameter springs, about 30 mm long. At full compression they were 15 mm long, so for a minimum gap between the uprights of 7 mm, there had to be at least 8 mm of extra space for the spring to compress into.
• Drill 10 mm diameter holes about 10 mm deep in the fixed uprights where the springs will fit

HINT: When fitting the threaded inserts, it is best to thread them onto the end of the through bolt, just leaving enough room to put the hex key into the top of the insert, then, as you use the hex key to screw the insert into the hole, the through bolt keeps the insert aligned. (see photo) All-thread rod is OK for the through bolts, but I didn't have any with the M6 thread on it, so I used some 6 mm rod that I had on hand, and put threads on each end of it. (see photo)

• Mount a 60 mm length of 25 mm angle on the right hand fixed upright to catch narrow screws that may fall through the guides. (see photos) It directs the screws into the first collection box, and minimises jamming
• Cut a corresponding slot in the movable upright to allow clearance for the angle.
• The movable uprights should be clear of the baseboard by about 1mm. It makes adjustment easier but mostly, it stops them vibrating against the baseboard and causing excessive noise.
• Cut the 3 mm flat Aluminium to length, (500 mm)
• Drill and countersink mounting holes so it can later be screwed to the fixed uprights. Leave an overhang of 120 mm on the “feed” side and 40 mm on the “exit” side so that any screws that don't sort can be collected at the end.The flat guide has aluminium angle fixed under each end to give more rigidity and to direct the screws.

NOTE: This flat guide has a 45 degree chamfer filed on the top and bottom of the front edge so that the smaller screws can freely tip past the underside edge, and the longer screws don't “balance” on the top edge. (see photo of the long screw balancing)

• Once all the cutting and bolting is done on the flat aluminium guide, it can be fixed to the uprights with 2 x 30mm screws. The chamfered edge of the flat guide must be directly in line with the outer face of the sorting plate. To get the position right, the sorting plate can be temporarily screwed to the uprights.
• Install a 60 mm piece of 10 x 10 mm angle on the top of the movable guide to “push” loose screws over to the slot. (see photos)
• Bolt the top baseboard loosely to the bottom board. The securing nuts should not put firm pressure on the rubber spacers, because this increases noise and vibration transmission.

Step 5: The Down Tubes:

Important: The upper 20 x 80 x 90 mm block that supports the vibratory end plate must be mounted before the receiver tubes are installed, because unless you use a pocket screw technique , once the tubes are in place there is no clearance to drive the screws into the block

Eight of the ten tubes are attached to 2 battens 40 mm x 20 mm x 270mm between the fixed uprights behind the sorting plate. (see photos and drawings)

The first 2 down tubes - for the 10mm and 13 mm screws - are installed on the movable guides so that the screws fall down them reliably: Short screws with large heads tend to overbalance and fall to the front of the sorting plate rather than going backwards through the slot.
A 70mm entry slot is needed in these first 2 tubes with the bottom edge of the slot bent out about 2mm towards the sorting plate. This is to deflect falling screws into the tube and stop them jamming against the sorting plate, and the reason for the long slot is so that 62mm screws (the longest that this machine can sort) will clear the bent tab on the bottom of the slot.

A section is cut out of one side of each tube to allow the screws to fall through. The cut outs on tubes 3 - 10 are 5 mm longer than the step in the sorting plate. A short (broken) jigsaw blade in the jigsaw cuts the slot very well, but a hacksaw can be used. A router with a flush trim cutter is ideal to take off the last little bit of aluminium left over from the jigsaw cut. A file can be used but its messier and takes longer.

The 62 mm down tube is shorter than the rest to allow enough clearance for the 62 mm screws to exit the tube,

The eight tubes are screwed to the battens with countersunk 12mm screws. 8mm access holes are drilled in the lower portion of the tube so that the screw head and the screw driver fit through. (see photos)

The tubes are kept perpendicular to the battens and with their tops aligned and the lower screw installed first, because the limited access makes it much harder if the tubes are already fixed at the upper end.

If the assembly is done with the battens between the fixed uprights, it is much easier to maintain spacing and orientation. 1.5mm plastic spacers are placed between each tube to ensure a consistent spacing. Each tube is held hard up against the spacer while drilling the pilot holes. Tubes are positioned and screwed down one at a time.

Once completed, the tube array is used to mark out the steps on the sorting plate. It is important that the steps on the sorting plate extend to the inner edge of the next largest tube. If they are short of this, screws fall out the front instead of going down the tubes. (See photo of wrongly cut section)

Once the plate is cut out and screwed into position, the tube array is placed against the plate, 1mm clear of the the flat aluminium guide at the top. (to minimise vibration noise) The battens are screwed to the uprights with 60 mm screws through the fixed upright at each end.

Step 6: The Metal Sorting Plate:

The metal plate is 110mm high and 340mm wide, spanning across both uprights.

2 x 3mm mounting holes are drilled: on each upright, 30mm from the top & bottom of the plate.

The holes are countersunk for 25mm screws. The heads should not stick out where passing screws might run into them.

Using the tubes as a guide, mark out the steps using a set square and ruler, then cut the steps and file them to size.

Before screwing the plate on, it's best to stick gaffer tape all over the the back so that the square tubing doesn't vibrate against it and cause noise.

Clamp the plate against the fixed guide and drive the 25mm screws into the uprights.

Test different screw sizes to ensure that they will exit through the holes where they should, and make any adjustments.

Step 7: The Movable Guide:

Drill and countersink screw holes for 30 mm screws in the 25 x 25 aluminium angle.

Drill corresponding pilot holes in the movable uprights, ensuring that they are 270 mm apart and vertical. Don't screw the angle on yet.

To prevent jamming of screws in the V-shaped feeder section, the vertical part of the upper (front) movable guide was cut off, beginning at the rear of the right hand support block, and going to the feed-in end of the angle. Although this reduced jamming, removal of this vertical section meant that the remaining thin horizontal aluminium strip was not well supported, which caused even worse problems! The solution was to bolt a peice of steel 1.6 mm x 20 mm x 100mm underneath the flat guide to stiffen it. (see photos) The bolts used are the ones that hold the guide onto the aluminium. At first I thought that putting this extra thickness of plate under the guide would raise it up and make it uneven, but this is not discernible and doesn't negatively affect the sorting. Jamming is vastly reduced, and sorting is much better.

To improve sorting of short screws with large heads the upper movable) guide needs to be cut to allow these screws to fall away from the sorting plate rather than through it.

Why do this? Many short screws with large heads have their point of balance exactly where the head meets the screw shaft. When these screws tilt down to go through the slot, they typically strike the slot about ½ way along the screw thread, (past the point of balance in the wrong direction) which causes the screw to fall backwards against the movable guide, and get stuck there, blocking the movement of all the screws that are banked up behind it.

If there is a slot just where the edge of the screw head would strike on its way to resting against the guide, the screw falls back through this slot and is guided down into the receiver tray through the front down tube.

Short stainless steel ramps behind the 10mm and 13 mm slots ensure that all screws are directed back down the front of the sorting plate and into the collection tray.

Where the guide goes past the 62mm downtube, a notch must be cut out of the vertical part of the movable guide, to approximately 1 mm below the upper face of the lower (fixed) guide.

This is necessary because when 62mm screws tilt through the 25 mm down tube, the point of the screw touches the back of the tube before the screw has enough angle to fall off the guide and into the tube.

By doing this modification, when the screw head tilts, the edge of it goes into the cutaway and it falls off the guide and into the tube.

Screw the Aluminium guide to the top of the movable uprights.

Fit the 30mm springs over the through bolts, with a washer over the spring

Fit the movable uprights onto the through bolts and secure with: 1 x washer, 1 x 6 mm adjustable nut and a 6 mm wingnut. There is a 30mm x 6mm x 2mm piece of steel welded to the nut which makes adjustment easy. (see photo) It is less tedious than using a spanner to adjust a nyloc nut, and unlike a nyloc nut, it doesn't wear out. The wing nut locks the adjustment in place. The bigger the wings on the wing nut, the easier they are on your fingers.

Step 8: The Vibratory Section:

The vibratory section consists of 2 x 20 mm x 80 x 90 wooden blocks which transmit the vibrations to the sorter, 1 end plate, 15 mm x 210 mm x 185 mm and the vibratory motor.

An old low-power orbital sander connected to an AC motor controller was used with the body of the sander fixed to the end plate. The vibrations are easily controllable, and transfer gently and evenly.

To prepare the sander, the bottom plate that holds the sandpaper was removed, the eccentric wheel temporarily removed while the dust extractor port was unscrewed and removed . The eccentric wheel was put back and the retaining screw and washer replaced. NOTE: the retaining screw that secures this wheel is a LEFT hand thread. To loosen it you turn it clockwise – the opposite of a normal screw.

Orbital sanders are an ideal choice for this job, as they are designed to withstand constant vibration. Motors without ball or roller bearing races will not last long in this application.

A notch 10 mm deep by 35 mm long is cut in the top of the end plate, 75 mm from the lower (front) side, and 95 mm from the higher side, to accommodate the overflow tin. (see photos) A 70 mm hole was made on the end plate where the sander was to be fitted so that the eccentric weight had room to move, the sander was screwed to the end plate, and the end plate screwed to the 80 x 85 mm wooden blocks with 50 mm chipboard screws.

It's best to put a safety screen over eccentric weight to prevent accidental contact. (See photos)

Step 9: The Feed Ramp:

2 pieces of wood with a 45 degree chamfer are bolted to the upper surface of both guides, and 16mm aluminium angle is screwed onto them. The wood on the lower feeder arm is 8mm thicker than the one on the upper arm, so that the trough is an even “V”. (see photos) It is important for this “V” to be fairly even at the start, so that the screws orient properly.

To form the trough, a piece of 15x15 angle is pop riveted to the piece which will fit onto the wood. After riveting, 2 x 4mm screw holes are drilled in each set of angles for the attaching screws.

NOTE: The rivet is positioned so that the flatter “head” touches the wood, and a shallow 7mm indentation is made in the wood to accommodate the protruding rivet head.

After drilling pilot holes, the 2 angle sets are screwed to the wood using 12mm screws. (Too short to reach the aluminium guide.) The edge of the angle must not overlap the edge of the wood, which could create a narrower gap than the rest of the guide rails.

The screws slide down a small wooden wedge at the end of the fixed side of the ramp. This helps prevent screws falling on top of one another and causing a jam. (see photo)

Step 10: The Feed Tin:

I wasn't happy feeding screws piecemeal onto the feed ramp so I opted for a “circular” feed tin for the end of the feed ramp. The feed tin consists of 2 parts: The “circular” tin, which is actually a 12-sided tin, and a “V” shaped chute to interface with the feed ramp.

This assembly was made from stainless steel because it is easy to spot weld. After making a number of cardboard models, the components were cut out, folded and spot welded together.

After welding, the base of the “round” tin was domed upwards using a ball-pein hammer so that screws are forced to congregate around the edges.

Initially the vibration in this tin tended to be under-damped and it threw screws everywhere. Carefully taping the inside of the tin with Gaffer tape largely fixed this, but even so, screws cannot be put into the feed tin until the machine is up to speed, because it goes through some extreme resonances on the way up to working speed. Taping the inside of the tin also caused a large drop in the noise of rattling screws. (Yay!)

Once the unit is assembled, it is screwed to the fixed part of the feed ramp with 2 x 4mm screws, allowing a clearance of 3 – 4 mm above the bottom of the “V” of the feed ramp. In practice, some bending/tilting of the assembly will probably be needed to get the screws to move smoothly around the edge and feed into the delivery chute, not just all gushing out the exit together. When locating the attachment screws, it works best to just put 1 screw in place, move the feed tin up & down until an optimal feed rate is reached, then drill the other hole and put the other screw in.

In operation, a handful of screws can be dumped into the tin, and they will (with some help) proceed around the outside of the tin until they fall out into the delivery chute.

Step 11: The Overflow Tin:

Because this sorter was built to sort all kinds of different sized screws, inevitably there are larger and smaller gauge screws in the mix. The overflow tin fits under the feed ramp and catches screws that are small enough to fall through the guides. These smaller gauge screws are sorted later, with the guides set to the appropriate width.

From the photos you can see that the tin fits into a notch in the end panel, and because it also rests on the 80 x 85 mm top block, it is stable but to stop it vibrating out of place, a pilot hole is drilled through the bottom of the tin and into the bottom of the slot that it fits into. A 50mm screw is screwed into the wood, then cut off & filed to leave 10mm protruding. A larger hole is then drilled in the tin to accommodate the screw shaft.

My tin has a 12mm deep cutaway at the end where the screws feed into the guides from the feed ramp, because longer screws would otherwise hit the edge and stop. A better solution would be to move the tin 12 mm lower and re-design the overflow tin.

The pattern for the tin can be drawn onto a piece of scrap sheet metal or the fusion 360 drawing could be printed and stuck on to the metal to make the job quicker.

It is then cut out & folded, and spot welded together. It could also be riveted or screwed etc.

Unpainted metal, eg. thin Stainless steel is easiest if you are intending to spot weld it.

The tin, the slot in the backboard and the back surface of the tin that rests on the 80 x 85 mm block should be covered with something to stop vibration noise. – I used old inner tube rubber and gaffer tape but any absorbent material, even cardboard would work. (See photo)

Tip: Stainless steel sheet is found in abundance in the tumbler section of many old clothes dryers and sometimes as a cover on microwave ovens, thrown out for kerbside pickups.

Step 12: The Collection Boxes:

Using the jigsaw with a shortened blade, one side is removed from lengths of 25 x 25mm square aluminium tubing. (best to do it before cutting into individual box lengths)

The rough edges are trimmed using the router with a flush edge cutter.

The resultant “U” section is cut into 110mm lengths, and a piece of angle riveted into each end to form a box. The rivets cause just the right clearance for the boxes to sit directly under each down tube. The riveted ends are super glued to the U section for added strength, and a piece of 50mm gaffer tape is stuck over the non-riveted side, and folded over onto the underside of each box to dampen any vibration noise.

With the boxes in position, 2 cleats are nailed to the baseboard to hold them in place with a 1 – 2 mm clearance between the cleats and the boxes (see photos)

Step 13: Performance Review:

Whilst the machine is somewhat “automatic” it has to be carefully monitored to ensure an even feed of screws and to clear the guides of stuck screws. In the video you may notice me pushing the screws around with a bamboo skewer so that the screws end up “point down”. Short screws with large heads tend to sit upside down.

To sort screws of all different gauges, the gap between the guides must be altered for each gauge/head size.

If you look carefully at the other online videos, you may notice that the screws being sorted are all the same gauge, head size and design, and are fed very carefully and sparingly. I have tried to make this machine flexible enough to sort a variety of screws, but there are limitations....

To use the machine with a lot of mixed screws, it's best to do an initial sort to classify the screws roughly into gauge/head size:

1. Set the guides so that they will correctly sort the largest screw that you have in the mix
2. Turn on the machine and put a good handful of screws into the feed tin. They need to end up in single file as they come off the feed ramp. They will mostly sort according to head size, and many will also sort into their “proper” size bin.
3. Watch out for odd size or larger screws jamming in the slot. If this happens, dig the screw out with long nosed pliers & sort it later.
4. Once the preliminary sort is done, you will see that many of the screws have fallen into the overflow tin, and the rest are roughly sorted into length/head/ gauge size. . (see video)
5. Sometimes it may be advantageous to re-sort each tray individually because when the screws are all “similar” they tend to interfere with one another less, and this gives a better outcome.
6. Starting with the largest gauge screws, re-set the guides to the correct width for the screw size & re- sort them for length.
7. Repeat this with the screws that fell into the overflow tin.

During the initial sort for gauge, some screws fall directly through the guides without going through the tubes, especially if they have small heads and in this case their direction is fairly random and they sometimes bounce out of the collection boxes and onto the floor. A plywood petition can be put at the front will minimise this.

Positives:

The machine works best on countersunk screws longer than 25 mm, will handle partially or fully threaded shanks and thread types, and sorts screws down to 10 mm.

The critical dimension is the screw head size, and to a lesser extent, the screw shaft size, as these determine the spacing between the guides and therefore, which screws will sort properly.

Though it might seem tedious, It is faster and easier than sorting screws by hand, and differentiates well between screws of only slightly different lengths

Once it is properly set up to sort screws of the same design and gauge, it is fast and reliable.

Negatives:

It's not 100% accurate, especially with mixed screws of different gauges.

Any screw that is very short and fat can't be sorted by this machine. (see photos) Screws or bolts with heads that are large or flanged, or very deep or very small in relation to their thread gauge, bolts with fitted washers or screws or those that have hexagon heads, will not sort properly, no matter what their length. They either fall off the end, get jammed in the feed chute or the guides, or sort into the wrong box.

If a screw gets jammed it dampens the vibration and causes the screws behind it to bank up and it must be manually removed.

Whenever head & shaft sizes change, the guides must be reset at both ends using a sample screw to check for free passage. (See Felix's video for adjustment procedure) This only takes a couple of minutes.

The receiver bins on this machine don't hold enough screws although with slight modification they could be made 2 or 3 times deeper.

The machine can be noisy unless the speed is carefully controlled.

At certain vibration speeds and specially at startup, the feed hopper can go into wild resonance and throw screws everywhere. Best not to have screws in the hopper at this time.

It would be better if the round feed hopper was deeper. Sometimes the screws bounce out of it.

You may be shocked (as I was) to discover just how many different sizes and types of screws you have.