Dr Ian Plummer

http://www.oxfordcroquet.com/equip/swingtrainer/index.asp

Oxford Croquet

By John Hobbs

1. Introduction

The idea of this device is to perfect the straightness and smoothness of your mallet swing. It consists of two panels of plywood, separated by a bit more than a mallet width, between which you have room to go from a backswing to a fairly high follow through. Using the trainer you can aim a ball at a target and hit 100% of the time. Once your muscles and mind have learned how to do this you can step outside the trainer and repeat the exercise and achieve nearly 100% success. Reg Bamford, who invented the device, gets 22 or 23 hits out of 24 from the east boundary to the peg. He spends a lot of time using it, with demonstrable results.

You can spend time just swinging the mallet to get into a 'groove' with your swing. You can then put a ball into the shooting position and see where it goes. Put a target there, or move the trainer round so that it is correctly aligned and then fire real balls for a while. There is a box that you can stick in front of the trainer so that it will collect all balls and roll them gently back for aligning again. The box is best used up against a wall, with some heavy objects to stop it moving, or, if it is on grass you can put two 6" nails through holes at the side to stop movement. The trainer itself is designed either to be used on a carpet or solid floor, or outside on the lawn, where again you can put two nails into the ground to stop sideways movement of the panels.

To transport the trainer it can be dismantled into four panels that then stack together and hold the legs and supports inside as a kind of sandwich. Two bolts can holt the four panels together for putting into a car boot. There is a more expensive version that can be bolted together to travel by air, but knowing how handlers abuse objects it may still take some damaging punishment.

2. Using the Trainer to Improve your Swing

The idea of the trainer is to condition your mind and muscles to have a perfectly straight swing that results in predictably straight shots. With the trainer the balls always go in the same direction because the mallet is always in line. When you have done enough practice swings (and I don't know how many that is!)(1) you stand aside and repeat your stance and swing and your mind and muscles should have learned what to do and you should hit with above average consistency.

The trainer can be used either to upgrade your shooting accuracy generally, or it has been used to restore reliability of good shooting if it has gone off for some undiscovered reason or other.

2.1 Using the Trainer in a Confined Space

Always try to have the trainer on a carpet. There are benefits from just practising your swing, without a ball. I think in my case just having a few swings with the trainer in the garage can set me up for accurate shooting when I arrive at the lawns for play.

If you cannot shoot balls across a lawn then you need a way of stopping them. The following options come to mind. A rolled up blanket against a wall, a heavy packing case, some plastic foam (it may be a bit too lively and return balls a bit smartly. At a club use one of the wooden planks used to stop boundary balls.

2.2 Having a Target to Aim at

It is better to have a target to be aiming at, either with the trainer or when swinging without it. Reg Bamford suggests half a scrap ball with a stake or nail through the cut face, so that even when hit it does not move, but looks like a normal ball. The half ball can be used if you cannot shoot across the lawn at the peg or the side of a hoop.

Reg uses the trainer for over an hour at a time. I think lesser mortals will benefit from much less time, especially if you make sure that your swing is one that is natural and gives you the best chance of being consistent.  All the trainer then does is make sure that your mind and muscles remember what you should be doing.

3. To Unpack and Ussemble

Rutger Beijderwellen unveils his new prototype swing trainer to an intrigued international audience at Surbiton Croquet club

Refer to the diagram (Fig 1) that shows the numbering of the holes in the panels and also the way in which the nuts and washers are assembled.

Undo the bolts that hold the panels together when packed and lift off the outer panel and then the inner panel.  You can then take out two pairs of legs, labelled F (front) and R (rear), joining bars that connect front and rear panels and the 6 connecting rods and two 6" nails. There is a tin of nuts and bolts, Take out the 70mm bolts and store them for when you want to pack the trainer up securely, as opposed to just putting the panels in the back of the car loosely. The tin contains all the nuts bolts and washers you need to put front and rear together; the connecting rods will have to be separate.

The threaded connecting rods have double nuts on them, so that you can lock them together and they will remain fixed to the width you want for your own mallet. I have set them at about 60mm, which should suit any head width, but if you want to decrease the gap between panels you will need the two 10mm spanners to unlock, move and then relock each pair of nuts. Alternatively you can just undo them and move as desired but be aware that if you dismantle and reassemble the setting may change.

Connect the long joining struts to the front and rear sides. The struts are marked RF and RR for right front and rear and LF and LR for the left and are connected to the panels with countersunk 35mm long M6 screws, on which you put a small washer and a nut. Tighten these to keep the panels from moving relative to each other. Attach the small connecting struts as well to keep the panels in line, using 25mm length screws. When you have connected up one of the sides, put in the connecting rods with a large washer on each side of the plywood. The rods go into holes 1, 2 and 3 in the front and 4, 5 and 6(optional) in the rear. Rod 1 can go either at the highest hole in the front panels, or half way down in 2A, or you can dispense with it if it inhibits your follow through. Two of the connectors are 11cm long and these are for the leg positions. Put a nut on each rod, but don't bother to tighten fully, since it helps when fitting the other side. Lay the side down and put large washers on each of the rods. Connect up the other side and lay it on top of the first, threading the rods through the corresponding holes. Put large washers on all the rods and for those that don't have legs (1, 3, 4 and 6) add a nut and tighten all their nuts up. For the rods (2 and 5) that have legs attached, fit the leg, then a small washer and a nut (there is enough length for there to be a small nut, then the leg then a small washer and another nut – it doesn't make much difference). Tighten everything up and the whole thing should now be stable. If there is any problem with height or lop sidedness you can move a leg out of the vertical to lower that side. As a last resort you can bend the steel that attaches the legs to alter the angle and therefore the height.

If you have the trainer on grass (as opposed to indoors) then you can put a 6" nail through the nylon block at each side in the middle to add stability and preserve the width between the sides. Put them in about 2", just enough to stop sideways movement.

3.1 To Dismantle and Pack for Short Transport

Dismantle everything, keeping track of all the nuts and bolts and put together a sandwich of the four main panels, secure the legs and side bars as a bundle and put in the boot of  a car.

3.2 To Dismantle and then Assemble as a Packed Sandwich for Transport

Undo everything and put all the screws and bolts into the tin. Start packing with the rear panel marked  RR  (outer side uppermost) and put the 70mm bolts through the holes. Put the front panel (LF) with the wooden retaining pieces on next and put the legs, the connecting struts, the 6" nails into the space where they are stored.

Now put the remaining front panel on and the remaining rear panel, put a small washer and nut on each bolt and the whole unit is secure. Don't tighten too much or you just bend the panels.

4. Construction

The trainer consists of two 6mm (¼") exterior grade plywood panels, shaped to allow as full a swing as possible, held together by spacing rods and having legs front and rear for support. Each panel has a front and a rear part, so that all four parts can be cut from a single 8' × 4' sheet. If you have a larger sheet, or use two sheets you can make allowance for a higher swing on the follow through, but you may have to make the front more stable. You could use a thicker ply for strength, but it increases cost and weight.

The history of the trainer is that Reg Bamford originally wanted it to hold a mallet between the panels, like a sandwich. This dictated the design, but was not used by Reg, so the next constraint was that the pieces should pack together and sandwich the legs and other bits between them and bolt together for transport and delivery. If this facility is not required it cuts out some minor work. Feedback from Jeremy Dyer has lead me to think that it may be a good idea to strengthen the panels by gluing strips of wood to them, especially the front pair (he remade the whole thing in 9mm MDF, but it weighed a ton). If this is done and you still want to pack the legs in the middle it will be a question of making sure that the reinforcing and the bits that hold the legs do not interfere, neither do they snag the long connecting bars.

4.1 Cutting Out the Panels

The shapes of the four parts are as shown on the sketch. These should be marked out and checked to ensure that you get the maximum utilisation of the 8×4 panel, then cut with a fine jigsaw. I suggest that you make paper templates of a front and rear and put them on the 8×4 to check that the four pieces will fit. Experiment with altering the shape to provide more area to prevent your mallet from coming out of the trainer or hitting the connecting rods, when you swing. I have indicated on the cut-out plan where you can increase the size. The measurements quoted for the panels are approximate. To minimise damage by tear out, the direction of cut should be arranged so that you are always causing the tear out in the waste piece rather than the panel. This means you have to change direction from time to time, rather than just go round the perimeter. If you are making more than one at a time you can bolt 3 or 4 sheets together, but I suggest that you make a single one first, to check the sizes are suitable and then use the panels as templates.

4.2 Holes for Connecting Rods

The connecting rods are best made from lengths of M6 rod that can be purchased in 1m or 0.5m lengths. If you use Whitworth ¼" then that is more or less the same. Use a 6.1mm drill to drill the holes for the rods. Put the pairs of panels together, clamp them and then drill the holes through the pair, but put a piece of scrap wood underneath so that the drill doesn't cause damage when it breaks through the bottom ply. The positions of the holes are not critical. Put short nuts and bolts through two of the holes in order to keep pairs of panels aligned and sand round the edges to get rid of all rough spots and potential splinters. Use a plane for the straight edges.

4.3 Connecting Bars

The front and rear parts of each side have to be connected with strong enough pieces of wooden connecting bar, about 75cm, or longer, (2' 6") and about 20mm by 15mm. Label each bar on the inside with RR, RF and LR and LF to distinguish front and rear and left and right. Drill 6.1mm holes through near the ends and each side of the middle of each connecting bar. Lay front and rear bits of panel for one side on a large surface and line them up so that the front panel clears a croquet ball, i.e. 4" above the ground. Label the panels with RR, RF etc. It may be necessary to plane the edges where the panels meet in order to provide the correct level for the front panel and also to make a good butt join. Put the connecting bar high up on the two panels and drill part way into the plywood through each hole. Remove the connecting bar and drill completely through the four holes, making sure to have some scrap under each piece to avoid damage. It is advisable to have two short connecting bars that go at the bottom of the two panels, purely to keep them in register, rather than for strength. I make mine just 4" long with a countersunk bolt going through each side in the same way as the main bars.

Repeat this for the other side and then countersink all twelve holes on the inside so that you can use countersunk M6 bolts to hold the connecting bars to the plywood, with a washer and nut. The bolts need to be 25mm or 30mm depending on the thickness of the ply and connecting bar. Test out the required amount of countersink on a piece of scrap ply and set up a pillar drill to repeat the required depth. Fit and tighten all the bolts for each side.

4.4 Spacing Rods

You now need to cut the M6 rod into 10cm lengths, grinding the ends smooth and chamfered so that the nuts will start easily. Put two pairs of nuts on each rod, so that the outside distance is about 6mm (¼") more than the width of your mallet (or 6cm for general use). Lock the nuts tight. Put 25mm M6 washers on either side of the ply and put a nut (loosely) on the outside for each of the six rods, for one of the sides. With that side either lying flat, or upright, offer up the other side, after first putting six more 25mm M6 washers on the rods. As you thread each rod through its correct hole in the other panel, put on another washer and a nut. Tighten all nuts only when they have all been fitted. It saves time if you have a 10mm socket spanner in a drill to do all the tightening.

4.5 Cutting the Legs

The trainer should now stand up correctly even though it hasn't got legs yet. The pieces of steel bar for connecting the legs may be available to buy as such, but I have found that they are a bit weak. I have found some suitable steel bits in a builders merchants, from which I can cut lengths of about 10cm (4") and drill a 6.1mm hole at one end and two countersunk holes to take 15mm × 3.5mm (½" or ¾" No. 6) screws into the wood of the legs. The metal has to be bent through about 30°, in such a way that the screws will go into the underside of the leg. Work it out first and then bend!

The legs need to be about 20 × 25mm and their length can be estimated once you have put the metal connectors onto the rods. I estimate the required length, cut the bottom at 30° and cut the top square, but a bit generously, so that you can trim a bit more off if the leg is too long. When the length is right, drill pilot holes for two c/s screws in each leg and fix to a steel bar. With the legs fixed you can check out the machine with a few swings and decide whether the clearance between the sides suits you. You could put the rear legs higher up the rear panel, so that they give greater stability through greater length and spacing apart on the ground.

4.6 Blocks to Take 6" Nails

Dismantle the trainer completely, in order to fix the nylon blocks in the rear panels and (optionally) fit retaining bits of wood so that you can store the legs and other pieces between the panels for travel. If you don't intend to move the trainer there is no need for the storage facility. The blocks I use to take a 6" nail and anchor the middle of the trainer into the grass, can be made of any suitable material, but I use some 1" square nylon section, that I cut into 1" lengths. I drill a 6.1mm hole through at an angle, so that the nails can be driven in easily. Drill two clearance holes into the rear panels so that the blocks can be attached, using 15mm × 3.5mm screws and countersink them. Drill pilot holes into the nylon blocks and use c/s screws to attach to the panel. If you intend to transport the trainer it is necessary to have the blocks at different distances from the end so that when the panels are laid on top of each other the blocks do not touch. Cut the heads off two 6" mails and then made two pieces of wood as handles, drilling them to take the nails. Put the nails in the handles and glue (I use superglue for speed and ease).

4.7 Strengthening (optional)

If you feel that you want the panels to be more rigid at the top, then glue strips of wood to them on the outside in the places I have indicated on the drawing.

4.8 Storing the Parts for Travel

To build the storage facility, first put the two connecting bars on top of the outside of the left front panel, as in the cut-out plan. Put the legs and short connecting bars, the 6" nails and connecting rods in a suitable layout and then cut wooden strips to go round the three sides of a box, using the connecting bars as the fourth side. If you have a suitable container for the nuts and washers that is less than 20mm thick, then this can also go in with the legs and rods, otherwise a tobacco tin kept separate can hold them. The width of the strips of wood needs to be just over that of the widest item to be stored (around 20mm). Retain the long connecting bars by having short pieces (4cm) to glue at the ends and the outside edge, as shown in the cut-out plan. Glue all the wooden pieces on to the panel and remove surplus glue.

If you want to pack the trainer up, the sequence for doing so is to put the rear right panel down, with nylon block sticking up. Put the left front panel on top, with the glued on retaining pieces sticking up and arrange the overlap so that it seems to minimise projections. Put the right front panel on top and finally the left rear panel, with block facing down. When all four panels are in place, drill two 6.1mm holes through all four panels, making sure that they come just outside the storage area and roughly in the middle of the panel, so that two long roundhead bolts will hold the four panels together as a bundle and hold in the legs and connecting bars. Fit 70mm roundhead bolts through the two sets of holes and put a washer and nut on each. The package should be easy to carry and put in a car, but there would have to be a lot of protection done if the parcel were to go through a delivery service. It is for this reason that trainers have to be delivered personally rather than go through the post.

4.9 Finishing and Staining

Sand any remaining rough areas and the holes drilled for the final retaining bolts, to make ready for staining. Use an exterior grade wood stain and put at least two coats on. It's a messy job and I hang each panel and piece from a ceiling hook, using a bit of bent wire. Clear up any runs that tend to start at the holes. After the final coat of stain, drill out all the 6.1mm holes again, because they will have part filled with stain.

You can now assemble the trainer for use or pack it up for delivery. Users need to have packing and unpacking instructions and my own are included with these building instructions.

4.10 Materials Required

I have used metric measurement and bolt sizes but if your supplies are in imperial and you think in imperial – just convert. The 8×4 panel is still that size, but is now 2440×1220mm

1. 8' × 4' exterior ply panel in 6mm (¼") or thicker if desired.
2. 2 long connecting bars approx 75cm × 20mm × 15mm in hardwood
3. 2 short connecting bars 10cm × 20mm × 15mm in hardwood
4. 4 steel brackets approx 8cm × 15mm × 2mm
5. legs approx 20mm × 25mm × 30cm (front 2) and × 25cm (rear 2)
6. 2 × 6" nails + wood for handle shape
7. 2 × 1" × 1" × 1" nylon block or similar
8. 6 × 10cm M6 threaded rod.
9. 26 × 25mm M6 washers for spacers & packing bolts
10. 16 × 10mm M6 washers for connecting bars and legs
11. 38 × M6 nuts.
12. 12 × c/s 25mm (or 30mm) M6 bolts for connecting bars
13. 2 × 70mm round head M6 bolts for packing up
14. 6.1mm drill or similar to make bolt holes.
15. 12 × 15mm × 3.5mm c/s screws.
16. (optional) reinforcing strips of wood, or bits of cut off ply.

The bolts, nuts and washers are best kept in a container or bag and may or may not fit in with the legs and connecting bars.

5. Diagrams

The diagram shows the general shape of the trainer and how the parts are bolted together, using a 10mm spanner.

Bamford Swing Trainer Assembled
Not to exact scale

Fig 2. Layout for Cutting

Cutout Plan for 8' x 4'
Dotted lines show ways of increasing space for swinging.

Comments

Reg Bamford writes in response to a query on using the trainer:

On 21/10/2010 22:44, Reg Bamford wrote:

I'm a big believer in the benefits of the Swing Trainer. John Hobbs made a couple for me, and I use it (I have one left) every 3 years as a Swing MOT.

You will notice a huge benefit (and some rather startling results during the practice regime itself if you follow mine) in

• your stance,
• your swing and
• your confidence.

The practice regime I follow every 3 years (I reckon the benefits last that long) is:

5 practice sessions, each lasting 2-3 hours within a 2 week period at the start of every third season (March/April). Each practice session consists of:

• Shooting 16 balls on the Trainer at the side of hoop 4 from the West Boundary
• Shooting (the same) 16 balls through Hoop 9 from the boundary* (without the trainer)
• Shooting (the same) 16 balls at the peg from the East Boundary**.

Repeat this series 6 times, so shooting 16 x 3 x 6 balls (288 balls) during the session

Every shot is taken while practicing visualisation and pretence that the shot is the final hit-in opportunity of game 5 in the World Championship Final. Concentrate as much as you can on replicating a match situation.

* Every second series of 16 balls is shot from halfway - i.e. about 4 yards, rather than 8 yards.
** Every second series, close your eyes once you have taken aim and play the shot. This accentuates your non-visual senses, particularly touch and feel, allowing a better focus on the mechanics of your swing.

If you can beat my record of 64 consecutive hits on the peg AND 32 consecutive hoop shots during one session, then you know you're swing is grooved. Good luck!