Clicky

Frequently Asked Questions

EXPRESS DUAL

Changing grinding stones (Video)

This operation should only be carried out by suitably trained personnel.

Loosen the nut on the stone carrier (sleeve and nut) whilst the assembly is still on the mainshaft. NEVER hold the sleeve and nut assembly in a vice. It could easily be distorted.

Carefully examine the new grindstone for any signs of damage such as chips or cracks. Also look for signs of water damage (a dark stain in one area that will leave a grindstone out of balance) If the stone is damaged or you are at all unsure, DO NOT use that grindstone. Make sure that the mounting surfaces of the grindstone are clean with no grit. The mounting faces of the stone carrier (sleeve and nut) should be similarly clean. Tighten the retaining nut by hand. Fully tighten once the assembly is fitted on to the mainshaft. Remember that the nut should be towards the left hand side of the machine from the operator’s position.

ALL new grindstones should be dressed after fitting. If the grindstone runs out of balance loosen the retaining nut and rotate the grindstone on it’s mounting about ¼ turn. Re-tighten the retaining nut and try again.

Dressing the grindstone (Video)

The video explains the steps required to dress the grind stone on an Express Dual.

Do you have to grind out any relief that is on a new reel?

Definitely NOT – the relief has no effect upon the cut.

Does it matter at what position you place the cutting unit in relation to the stone?

Not really. Large reels get slightly more relief if they are above the stone so the impact is felt strongly.

How do I know if the front roller brackets are correctly lined up?

The brackets must be set so that the front roller (and reel axis) are parallel to the grind stone mainshaft.

On older pattern brackets set them with an engineer’s depth gauge or measure off the front main member of the Express Dual – it is factory precision ground. Later adjustable (and retrofittable) brackets can be set to the scales provided.

How do you show a relief is being applied?

Colour the blades with a marker pen or use rusty blades. Grind hard and briefly and then examine the blades. You will see that only (mostly) the rear of each blade is ground, showing the relief being ground off the back edge of the blade.

How far down can the stone wear before it needs to be replaced?

Until the fork obstructs the grind.

How hard do I grind?

As hard as you feel comfortable, up until just before you see vibration/movement of the mower on the machine. The Express dual is designed to grind in this apparently aggressive way. If you do not grind hard enough, you will gain no ‘auto-relief’ from the springs in the feed columns

How long do I grind?

Until the grind noise drops off slightly but there is still good contact between the reel and the stone, and the blade edges are sharp.

Should I let the stone go off each end of reel?

No! The pressure from the springs in the feed columns will be released so that when the stone goes back onto the reel the compression may take more off the ends of the reel and it may not cut at the ends

A broken chain

It has been overloaded and has stretched. The mainshaft may not have been cleaned properly, resulting in too much effort to pull along it. Clean the mainshaft thoroughly, including the keyways, and the whole set of traverse transfer parts.

The traverse chain is very slack, why?

It has stretched. The mainshaft may not have been cleaned properly, resulting in too much effort to pull along it. Clean the mainshaft thoroughly, including the keyways, and the whole set of traverse transfer parts.

The fork is badly worn on one side.

Can be as a result of improper cleaning or bad maintenance.

The stone chatters and vibrates unevenly

The stone may need dressing.

The stone carrier sleeve and nut may be worn.

The traverse fork may be damaged.

The stone doesn't move along the shaft smoothly

This might appear as "shuddering" or "sticking" during the traverse rather than a smooth movement along the mainshaft.

Friction caused by trying to move along a dirty or improperly cleaned mainshaft.

Clean out below the sleeve with WD40. Spray fluid into the gap between sleeve and mainshaft from each end. Work the sleeve and nut back and forth along the shaft and spray again. Spray and clean the whole mainshaft and move the sleeve and nut along the whole length of the mainshaft. Wipe off any excess fluid. (In an extreme case the sleeve and nut may have to be removed for absolute cleaning).

What does it mean when the spark pattern changes? (Or a change in the grinding sound)

Nothing really. Sometimes it reflects a slight imperfection on the stone (dress it) – or perhaps the reel is not true. Sometimes vibration frequencies "resonate", try varying the reel spin speed slightly.

What does the digital feed display show?

The led balance lights show the relative position of one side of the mainshaft to the other so that a parallel grind can always be applied. The green led shows both sides are the same relative to the point at which the reset button was pressed (Where light even stone to reel contact is made across the length of the reel) An amber light on one side shows that more feed is applied on that side handwheel. A red led shows that the additional feed on that side is considerable. Winding the opposite handhweel will restore balance and the green led.

The numbers in the digital readouts approximate to "thou" (0.001") of feed.

What happens if I "spark out"?

You lose all relief.

What if the mower bearings are bad?

You will get a rough job but it may still cut. Obviously the reel moves on its bearings and the job being done will be only as good as those bearings.

When is the reel done?

Continue a firm grind until the grind noise drops off slightly but there is still good contact between the reel and the stone, The blade edges should be sharp on checking.

Where should the grind stone contact the reel?

It doesn’t matter. Just ensure that the stone touches the reel without touching the bedknife or brackets securing the mower to the grinder.

Why does one handwheel unwind?

The spring under the handwheel is too loose and needs to be compressed more.

Why does the feed (stone) seem to "jump" in on one side after applying an even cut?

Have you recently changed the grind stone/sleeve and nut?

The mainshaft bearing has been replaced on the shaft in the wrong place, so that the side arm is sticking in the feed column guide channel.

Look for "rubbing" between side arm and channel and re-position main bearing so that the side arm is free and in the centre of the guide channel.

To check, bounce on the handwheel, side arm and shaft should move up and down freely with no sticking, or Lift the side arm and shaft and let go, it should fall freely back onto the feed nut.

The stone may need dressing – dress the stone.

There may be some vibration resonance - try varying the reel spin speed.

The collar (Stone carrying Sleeve and Nut) may be worn.

Why has the grind become uneven?

The stone may need dressing – dress the stone.

There may be some vibration resonance - try varying the reels spin speed.

The collar (Stone carrying Sleeve and Nut) may be worn.

How can you be sure that a reel is not being “coned” during the grind?

Once the grind stone is set to the reel, apply an equal cut at each side of the machine (on current/recent Express Dual, keep the grind in the "green zone" of the feed display).

How can you check that a reel is not “coned”?

Have the  freshly ground, straight bedknife correctly positioned in the cutting unit but not fully tight (free as if to adjust). Push the bedknife against the reel; and check for contact at every blade across the reel. If there is a gap at one end, measure the gap with a feeler gauge. This is the amount to remove from the opposite end of the reel to true it up