Home |
Search |
Today's Posts |
|
UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
Reply |
|
LinkBack | Thread Tools | Display Modes |
#1
Posted to uk.d-i-y
|
|||
|
|||
Hayter Lawnmower Disc Blade Carrier - how to remove?
I am servicing a Hayter Hayterette mower and need to remove the large metal
disc that the bladelets are attached to so that I can replace them. I assume I undo the nut in the centre. But how to stop the disc/shaft turning? And does anyone know which way the disc rotates in use - I suspect that the bladelets are on the wrong way round! cheers Davy |
#2
Posted to uk.d-i-y
|
|||
|
|||
Hayter Lawnmower Disc Blade Carrier - how to remove?
Davy wrote:
I am servicing a Hayter Hayterette mower and need to remove the large metal disc that the bladelets are attached to so that I can replace them. I assume I undo the nut in the centre. But how to stop the disc/shaft turning? And does anyone know which way the disc rotates in use - I suspect that the bladelets are on the wrong way round! cheers Davy The blades are actually bidirectional work out which way it rotates by pulling the starter cord These are total buggers to remove..not sure the central nut is not reverse threaded? check. They have a woodruff key and IIRC a tapered crank as well. Heat may be needed and a scrap bolt in the crankshaft with a large mallet. I generally grind off the bolts that hold the blades. and leave the disk in place till its totally buggered, and then cut that off as well. |
#3
Posted to uk.d-i-y
|
|||
|
|||
Hayter Lawnmower Disc Blade Carrier - how to remove?
On Sat, 19 May 2007 19:00:28 +0100 Davy wrote :
I am servicing a Hayter Hayterette mower and need to remove the large metal disc that the bladelets are attached to so that I can replace them. I assume I undo the nut in the centre. But how to stop the disc/shaft turning? Wedge a suitable piece of wood between a blade and the mower body And does anyone know which way the disc rotates in use - I suspect that the bladelets are on the wrong way round! Usually clockwise seen from the top: the same way as they go when you pull the starter cord g -- Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk |
#4
Posted to uk.d-i-y
|
|||
|
|||
Hayter Lawnmower Disc Blade Carrier - how to remove?
Davy wrote:
I am servicing a Hayter Hayterette mower and need to remove the large metal disc that the bladelets are attached to so that I can replace them. I assume I undo the nut in the centre. But how to stop the disc/shaft turning? And does anyone know which way the disc rotates in use - I suspect that the bladelets are on the wrong way round! You may find the bolt has an anticlockwise thread. -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
#5
Posted to uk.d-i-y
|
|||
|
|||
Hayter Lawnmower Disc Blade Carrier - how to remove?
On Sat, 19 May 2007 19:00:28 +0100, Davy wrote:
I am servicing a Hayter Hayterette mower and need to remove the large metal disc that the bladelets are attached to so that I can replace them. I assume I undo the nut in the centre. But how to stop the disc/shaft turning? And does anyone know which way the disc rotates in use - I suspect that the bladelets are on the wrong way round! cheers Davy Any nut securing a blade on a rotating shaft, that is a saw,a grinder, a lawnmower blade holder, is designed to tighten up under rotation. Otherwise they'd be flying off everywhere. So, think about it, when the blade is rotating the nut is tightening in the opposite direction. So mark the rotation with a chalk arrow on the blade holder. Lock the blade holder somehow, clamp it to something. Turn your spanner in the direction of the arrow to undo the nut. They are *******s to undo. My mate who is a lawnmower mechanic uses an air rattle gun. Give it a blast of penetrating oil. Get a good fitting solid spanner. Try a lever on your spanner, or belt the spanner with a lump hammer. Failing that belt the nut round with a lump hammer and cold chisel. On grind a section off the nut and while it is still hot, belt it with the lump hammer and chisel Depending how solid you have it, it could be a piece of ****. Then again you could bend your shaft, but that's part of the fun of DIY innit? Regards Bill -- Bill http://www.builderbill-diy-help.com/ |
#6
Posted to uk.d-i-y
|
|||
|
|||
Hayter Lawnmower Disc Blade Carrier - how to remove?
Bill wrote:
On Sat, 19 May 2007 19:00:28 +0100, Davy wrote: I am servicing a Hayter Hayterette mower and need to remove the large metal disc that the bladelets are attached to so that I can replace them. I assume I undo the nut in the centre. But how to stop the disc/shaft turning? And does anyone know which way the disc rotates in use - I suspect that the bladelets are on the wrong way round! cheers Davy Any nut securing a blade on a rotating shaft, that is a saw,a grinder, a lawnmower blade holder, is designed to tighten up under rotation. Otherwise they'd be flying off everywhere. So, think about it, when the blade is rotating the nut is tightening in the opposite direction. So mark the rotation with a chalk arrow on the blade holder. Lock the blade holder somehow, clamp it to something. Turn your spanner in the direction of the arrow to undo the nut. They are *******s to undo. My mate who is a lawnmower mechanic uses an air rattle gun. Give it a blast of penetrating oil. Get a good fitting solid spanner. Try a lever on your spanner, or belt the spanner with a lump hammer. Failing that belt the nut round with a lump hammer and cold chisel. On grind a section off the nut and while it is still hot, belt it with the lump hammer and chisel Depending how solid you have it, it could be a piece of ****. Then again you could bend your shaft, but that's part of the fun of DIY innit? Regards Bill I've never failed to get the nut off OK. Mole grips on the disc and a 2ft bar on the socket set. On account of the woodruff key they don't tighten up that much. But the disk has usually stuck to the point where I decoded to attach blades in situ... The key is the key IYSWIM, rusted in place. |
#7
Posted to uk.d-i-y
|
|||
|
|||
Hayter Lawnmower Disc Blade Carrier - how to remove?
"The Natural Philosopher" wrote in message ... Bill wrote: I've never failed to get the nut off OK. Mole grips on the disc and a 2ft bar on the socket set. On account of the woodruff key they don't tighten up that much. But the disk has usually stuck to the point where I decoded to attach blades in situ... The key is the key IYSWIM, rusted in place. Dear Phil', So a mole grip on the edge of the disc and then manually hold the mole grip? The nut is supposed to be tightened to 40ft lb so might need 80ft lb to get it off?? Not sure I could hold a mole grip against 80 ft lb? Even then, you have found that the disc is usually rusted on. I am now wondering about taking it to the local dealer and getting them to remove the nut and disc??? Go on then, I know you are dying to be asked; what does 'the key is the key' and IYSWIM mean? cheers, Davy |
#8
Posted to uk.d-i-y
|
|||
|
|||
Hayter Lawnmower Disc Blade Carrier - how to remove?
Davy wrote:
Go on then, I know you are dying to be asked; what does 'the key is the key' and IYSWIM mean? IYSWIM = If You See What I Mean I think he is saying something about the Woodruff key (the key) is the pivotal thing (the key) but no doubt the Natural philosopher will be along shortly to clarify -- www.cheesesoup.myby.co.uk |
#9
Posted to uk.d-i-y
|
|||
|
|||
Hayter Lawnmower Disc Blade Carrier - how to remove?
soup wrote:
Davy wrote: Go on then, I know you are dying to be asked; what does 'the key is the key' and IYSWIM mean? IYSWIM = If You See What I Mean I think he is saying something about the Woodruff key (the key) is the pivotal thing (the key) but no doubt the Natural philosopher will be along shortly to clarify in a nutshell. The bloody key rusts into the keyway. Blowlamp and WD40 time and big mallets |
#10
Posted to uk.d-i-y
|
|||
|
|||
Hayter Lawnmower Disc Blade Carrier - how to remove?
The Natural Philosopher wrote:
Blowlamp and WD40 time and big mallets Used to know a chap (a stonemason) who used to call strenuous lifting which became any strenuous activity, "rid eyes an' big baws time" ("red eyes and big testicles" time) -- www.cheesesoup.myby.co.uk |
#11
Posted to uk.d-i-y
|
|||
|
|||
Hayter Lawnmower Disc Blade Carrier - how to remove?
On Sat, 19 May 2007 19:00:28 +0100, "Davy"
wrote: I am servicing a Hayter Hayterette mower and need to remove the large metal disc that the bladelets are attached to so that I can replace them. I assume I undo the nut in the centre. But how to stop the disc/shaft turning? And does anyone know which way the disc rotates in use - I suspect that the bladelets are on the wrong way round! cheers Davy Hi Davy, Sorry to have come late to this. If you're still struggling I can offer the following advice - some of which may already have been given 1) Stand in the usual driving position behind the Hayterette 2) Make sure the petrol tap is turned off and turn whole mower 90 degrees to the left so it is stood on its left side. 3) Walk round and look at the disc from the underside 4) Clamp MOLE wrench as hard as you can at about the 2 o'clock position 5) put socket/spanner/big spanner or whatever on retaining bolt and turn slowly anticlockwise. The retaining bolt is a normal bolt NOT as has been suggested it may be a left hand thread 6) the Mole wrench will connect and jam against the front offside of the deck 7) put on a bit/lot of pressure - as others have said a liberal dose of PlusGas and or heat may help although on the 2 ancient ones I have done where I don't think the bolts had ever been off this was not needed 8) Persevere! 9) When the retaining bolt is out, the thread in the crank is actually smaller than the hole in the disc through which the retaining bolt passes. Furthermore this hole is threaded to take a bolt to draw the disc off the crank. I'm not very up on bolt threads but I THINK it was described as 1/4" when I got it. It is about 7/16ths diameter and pitch is about 19 per inch. The head has three radii on it which I am sure indicates something! Over to someone else on this one. 10) As to the blade orientation. The polythene packet that the genuine ones (or it might be the bolts for the blades - you are going to replace those as well aren't you?!) has a nice little piccie showing how they mount. I've just had a look at my machine and from the where it is clear the rotation is anticlockwise viewed from underneath. In the normal operating position the chamfer on the blade is uppermost. I apologise if all this sounds patronising, it is not meant to be! I was struggling to describe positions without points 1-3! Don't forget to : a) change the oil whilst you're there - the drain plug is under - or over depending on your viewpoint - the disc! b) coat the crank and the retaining bolt with Coppergrease when reassembling Good Luck Please reply to group - email address is not monitored Ian |
#12
Posted to uk.d-i-y
|
|||
|
|||
Hayter Lawnmower Disc Blade Carrier - how to remove?
Ian wrote:
9) When the retaining bolt is out, the thread in the crank is actually smaller than the hole in the disc through which the retaining bolt passes. Furthermore this hole is threaded to take a bolt to draw the disc off the crank. I'm not very up on bolt threads but I THINK it was described as 1/4" when I got it. It is about 7/16ths diameter and pitch is about 19 per inch. The head has three radii on it which I am sure indicates something! Over to someone else on this one. I cannot conceive how screwing a bolt back into the crank after you have removed on from it will 'draw the disk off.' The normal method is to put a scrap bolt in the crank and hit it very hard with a mallet to break the seal between the crank and the disk. Allegedly. I chickened out. Apologies about the reverse threaded thing..I was thinking of a ride on I stripped last year where one or both of the blades had a reverse thread on .. 10) As to the blade orientation. The polythene packet that the genuine ones (or it might be the bolts for the blades - you are going to replace those as well aren't you?!) has a nice little piccie showing how they mount. I've just had a look at my machine and from the where it is clear the rotation is anticlockwise viewed from underneath. In the normal operating position the chamfer on the blade is uppermost. I apologise if all this sounds patronising, it is not meant to be! I was struggling to describe positions without points 1-3! Don't forget to : a) change the oil whilst you're there - the drain plug is under - or over depending on your viewpoint - the disc! b) coat the crank and the retaining bolt with Coppergrease when reassembling Good Luck Please reply to group - email address is not monitored Ian |
#13
Posted to uk.d-i-y
|
|||
|
|||
Hayter Lawnmower Disc Blade Carrier - how to remove?
On Wed, 23 May 2007 13:44:56 +0100, The Natural Philosopher
wrote: Ian wrote: 9) When the retaining bolt is out, the thread in the crank is actually smaller than the hole in the disc through which the retaining bolt passes. Furthermore this hole is threaded to take a bolt to draw the disc off the crank. I'm not very up on bolt threads but I THINK it was described as 1/4" when I got it. It is about 7/16ths diameter and pitch is about 19 per inch. The head has three radii on it which I am sure indicates something! Over to someone else on this one. I cannot conceive how screwing a bolt back into the crank after you have removed on from it will 'draw the disk off.' Hi NP The bolt concerned is NOT the retaining bolt and does not go back into the crank but into the disc.... The threaded hole (No1) in the disc is slightly larger than the threaded hole (No2) in the crank. The retaining bolt passes straight through hole No1 but screws into hole No 2 . A bolt of the correct size for thread of hole No1 is put in Hole No1 and the end of this bolt bears against the end of the crank- not being able to go into hole No2 since the bolt is larger than the hole. Tightening this bolt 'winds' - this might be a better word than 'draws' - the disc away from the crank. I'd try some ASCII art but the last time I tried I failed miserably...so I hope this additional explanation makes sense. Please reply to group - email address is not monitored Ian |
#14
Posted to uk.d-i-y
|
|||
|
|||
Hayter Lawnmower Disc Blade Carrier - how to remove?
Ian wrote:
On Wed, 23 May 2007 13:44:56 +0100, The Natural Philosopher wrote: Ian wrote: 9) When the retaining bolt is out, the thread in the crank is actually smaller than the hole in the disc through which the retaining bolt passes. Furthermore this hole is threaded to take a bolt to draw the disc off the crank. I'm not very up on bolt threads but I THINK it was described as 1/4" when I got it. It is about 7/16ths diameter and pitch is about 19 per inch. The head has three radii on it which I am sure indicates something! Over to someone else on this one. I cannot conceive how screwing a bolt back into the crank after you have removed on from it will 'draw the disk off.' Hi NP The bolt concerned is NOT the retaining bolt and does not go back into the crank but into the disc.... Ah. Got it. Now that may just make me do the disk removal thing and an oil change this week. Integral hub puller. Never knew they had one of those.. Shame you don't know the exact thread.. |
#15
Posted to uk.d-i-y
|
|||
|
|||
Hayter Lawnmower Disc Blade Carrier - how to remove?
"Ian" wrote in message ... On Sat, 19 May 2007 19:00:28 +0100, "Davy" wrote: 9) . Furthermore this hole is threaded to take a bolt to draw the disc off the crank. I'm not very up on bolt threads but I THINK it was described as 1/4" when I got it. It is about 7/16ths diameter and pitch is about 19 per inch. The head has three radii on it which I am sure indicates something! Over to someone else on this one. thanks for that Ian, I don't think many of us realised that the blade disc has a built in facility for its removal. Regarding which is the correct bolt to draw the disc off the crank; garden tools and mowers tended to have British Std Whitworth (BSW) threads. A 1/4" BSW has 20 threads per inch and a obviously screw diameter of 1/4"; but you say it has a diameter of 7/16ths - or maybe you meant across the flats? A 7/16th dia BSW is 14tpi so it can't be that. However a 7/16th dia BSF thread is 18 tpi - maybe? Not sure what you mean by it having three radii on it; but UNC/F bolts have three circles in a row - I wonder if this is what you meant?. A 1/4" UNC bolts has is 20tpi and 7/16ths across the flats - if you did mean 'across flats' then this is a good match to what you have. But a UNC thread is wrong for a British lawnmower. So my guess is that the Hayter Hayterette requires a 1/4" BSW bolt; but that someone gave you a 1/4" UNC bolt which will screw in to a 1/4" BSW thread; but a UNC thread is cut at 60 deg whilst BSW is cut at 55 deg; so the mismatch will give a weak interaction because the stresses are not transmitted through the flanks of the thread. But none of this is making sense to me because I think I understand you to be saying that your withdrawal bolt screws into a thread in the centre hole of the disc? - and that "When the retaining bolt is out, the thread in the crank is actually smaller than the hole in the disc through which the retaining bolt passes" The retaining bolt which goes into the crank has a diameter of about 5/16ths - larger not smaller than 1/4". I think my knickers are now sufficiently twisted to hand the subject back to you! cheers Davy |
#16
Posted to uk.d-i-y
|
|||
|
|||
Hayter Lawnmower Disc Blade Carrier - how to remove?
Davy wrote:
"Ian" wrote in message ... On Sat, 19 May 2007 19:00:28 +0100, "Davy" wrote: 9) . Furthermore this hole is threaded to take a bolt to draw the disc off the crank. I'm not very up on bolt threads but I THINK it was described as 1/4" when I got it. It is about 7/16ths diameter and pitch is about 19 per inch. The head has three radii on it which I am sure indicates something! Over to someone else on this one. thanks for that Ian, I don't think many of us realised that the blade disc has a built in facility for its removal. Regarding which is the correct bolt to draw the disc off the crank; garden tools and mowers tended to have British Std Whitworth (BSW) threads. A 1/4" BSW has 20 threads per inch and a obviously screw diameter of 1/4"; but you say it has a diameter of 7/16ths - or maybe you meant across the flats? A 7/16th dia BSW is 14tpi so it can't be that. However a 7/16th dia BSF thread is 18 tpi - maybe? Not sure what you mean by it having three radii on it; but UNC/F bolts have three circles in a row - I wonder if this is what you meant?. A 1/4" UNC bolts has is 20tpi and 7/16ths across the flats - if you did mean 'across flats' then this is a good match to what you have. But a UNC thread is wrong for a British lawnmower. So my guess is that the Hayter Hayterette requires a 1/4" BSW bolt; but that someone gave you a 1/4" UNC bolt which will screw in to a 1/4" BSW thread; but a UNC thread is cut at 60 deg whilst BSW is cut at 55 deg; so the mismatch will give a weak interaction because the stresses are not transmitted through the flanks of the thread. But none of this is making sense to me because I think I understand you to be saying that your withdrawal bolt screws into a thread in the centre hole of the disc? - and that "When the retaining bolt is out, the thread in the crank is actually smaller than the hole in the disc through which the retaining bolt passes" The retaining bolt which goes into the crank has a diameter of about 5/16ths - larger not smaller than 1/4". I think my knickers are now sufficiently twisted to hand the subject back to you! cheers Davy As I understand it finally, the way it all hangs together is this. The crank is untapered and fitted with a woodruff key in a slot. The boss of the disk is slotted for this key and by an large fits over te crankshaft. The crankshaft is end drilled for a retaining bolt, but this is an enormously loose fit in the disc, as this is fully located by the boss and the key, and the bolt merely stops it falling off. Removal of the bolt reveals that the end part of the disk is threaded and a bolt can be screwed into the disk, to bear on the crank end and push the disc off. So I might tale the disc bolt out and see what is there. Now I am fairly sure that around 1990 or so, Hayterettes did NOT have this arrangement..mine is 1995 but I never took the disc of myself yet. It got serviced once about 6 years ago at the service shop. It had never had even an oil change up till then. We USED to change the blades by angle grinding the heads off the bolts that hold them in, that part of the head that hadn't already been ground off by mowing lumps of bricks and discarded spanners and the like. Sine the bolts can't generally be removed any other way, there is no need to remove the disc as well. Just grind off the heads, and fit new blades and bolts. Flat side down and bevelled side up. Only if the disk is damaged need it be removed. Or if you really feel like draining the oil. Though I THOUGHT mine had a plug in the sump side where it could all be tipped out of. |
#17
Posted to uk.d-i-y
|
|||
|
|||
Hayter Lawnmower Disc Blade Carrier - how to remove?
"The Natural Philosopher" wrote in message ... .. Now I am fairly sure that around 1990 or so, Hayterettes did NOT have this arrangement..mine is 1995 but I never took the disc of myself yet. So I might tale the disc bolt out and see what is there Dear Phil' If your Hayterette was made about 1990 then it may well be metric. My hayterette and B&S engine was made in 1968 so might be different still. In my rambling discussion about bolt size, because all of the dimensions that Ian gave were imperial, I had not considered that Ian's machine might be recent and hence metric. Let me know what happens if you have a go at getting the disk off. I am losing the courage to take off the blade disc retaining bolt since if the head shears off leaving the bolt thread in the end of the crank then my old machine would probably be scrap! best wishes, Davy |
#18
Posted to uk.d-i-y
|
|||
|
|||
Hayter Lawnmower Disc Blade Carrier - how to remove?
Davy wrote:
"The Natural Philosopher" wrote in message ... . Now I am fairly sure that around 1990 or so, Hayterettes did NOT have this arrangement..mine is 1995 but I never took the disc of myself yet. So I might tale the disc bolt out and see what is there Dear Phil' If your Hayterette was made about 1990 then it may well be metric. My hayterette and B&S engine was made in 1968 so might be different still. In my rambling discussion about bolt size, because all of the dimensions that Ian gave were imperial, I had not considered that Ian's machine might be recent and hence metric. Let me know what happens if you have a go at getting the disk off. I am losing the courage to take off the blade disc retaining bolt since if the head shears off leaving the bolt thread in the end of the crank then my old machine would probably be scrap! That does NOT happen. That bolt is really high tensile steel. But if all you want to do is replace the blades, just grind the bolts off and leave the disc where it is. best wishes, Davy |
#19
Posted to uk.d-i-y
|
|||
|
|||
Hayter Lawnmower Disc Blade Carrier - how to remove?
On Sat, 26 May 2007 20:00:39 +0100, "Davy"
wrote: thanks for that Ian, I don't think many of us realised that the blade disc has a built in facility for its removal. It's very handy! Regarding which is the correct bolt to draw the disc off the crank; garden tools and mowers tended to have British Std Whitworth (BSW) threads. A 1/4" BSW has 20 threads per inch and a obviously screw diameter of 1/4"; but you say it has a diameter of 7/16ths - or maybe you meant across the flats? A 7/16th dia BSW is 14tpi so it can't be that. However a 7/16th dia BSF thread is 18 tpi - maybe? The outer diameter of the thread is, as near as I can measure it 7/16th. The AF is 5/8th. It could very well be 18 tpi so is probably 7/16th BSF Not sure what you mean by it having three radii on it; Looking end on at the head with a flat horizontal there are three lines one pointing to the top flat (12 o'clock), and the other 2 at 120 degree intervals (i.e pointing to about 4 and 8 o'clock). Does this help identify it each but UNC/F bolts have three circles in a row - I wonder if this is what you meant?. No A 1/4" UNC bolts has is 20tpi and 7/16ths across the flats - if you did mean 'across flats' then this is a good match to what you have. But a UNC thread is wrong for a British lawnmower. So my guess is that the Hayter Hayterette requires a 1/4" BSW bolt; but that someone gave you I actually got it at a local garden machinery place who knew about the technique when asked and also knew the correct (allegedly) bolt to use as the withdrawal tool. But he didn't give me it! a 1/4" UNC bolt which will screw in to a 1/4" BSW thread; but a UNC thread is cut at 60 deg whilst BSW is cut at 55 deg; so the mismatch will give a weak interaction because the stresses are not transmitted through the flanks of the thread. My knickers also twisted at this point! But none of this is making sense to me because I think I understand you to be saying that your withdrawal bolt screws into a thread in the centre hole of the disc? - and that "When the retaining bolt is out, the thread in the crank is actually smaller than the hole in the disc through which the retaining bolt passes" The retaining bolt which goes into the crank has a diameter of about 5/16ths - larger not smaller than 1/4". All my 'measurements' relate to the bolt to draw off the disc. This bolt _is_ of a larger diameter than the retaining bolt I think my knickers are now sufficiently twisted to hand the subject back to you! cheers Davy In reply to the other issue in the thread (no pun intended) concerning age of the equipment and the possibility of metric.......my 'new' machine which definitely has this arrangement was bought 'just' secondhand in about 1989/1990 . I think it was made in 1988/9. Other bolts for handles cowlings etc are, I'm pretty sure, metric. My 'old' machine is significantly older - given to me to tame the jungle when we moved in here in 1987. The FIL was not known for his generosity so I guess it was totally depreciated by then! I guess manufactured at the latest 1975. Now, it doesn't have any metric bolts on it to my knowledge and I don't think I have ever had the disc off but I _THINK_ it was the donor who told me how to get the disc off using the integral hub puller. If it wasn't peeing down I could go and try and get the retaining bolt out I suppose but having been stood outside for the last 2 years and not been used other than for pinching spares for the last decade that could take a while!! Please reply to group - email address is not monitored Ian |
#20
Posted to uk.d-i-y
|
|||
|
|||
Hayter Lawnmower Disc Blade Carrier - how to remove?
"Ian" wrote in message
... On Sat, 26 May 2007 20:00:39 +0100, "Davy" wrote: Regarding which is the correct bolt to draw the disc off the crank; Looking end on at the head with a flat horizontal there are three lines one pointing to the top flat (12 o'clock), and the other 2 at 120 degree intervals (i.e pointing to about 4 and 8 o'clock). Does this help identify it yes, this is a 'unified screw' bolt; the bolts have three equally-spaced radial markings, the nuts would have three circles. The bolts should also have a figure at the 6 o'clock position which denotes the grade of steel and hence the maximum tightening torque; if this is missing then the bolt is low-grade steel. In which case the maximum torque that should be applied to the bolt is below 65 ft/lb - more than this and you risk damaging the thread or shearing off the head. The closest match to your description is a 7/16 UNF bolt which has 20 tpi. It will not fit a 7/16th BSW thread so my supposition about BSW being used was wrong. But you state that your machine is metric so we would expect a metric thread; a 7/16th diameter bolt equates to 11mm. The nearest common metric sizes are M10 (17tpi) or M12 (14.5 tpi) - so no metric equivalent of this size. Perhapsy Hayter changed the fastenings to metric by 89/90 but not the components? I look forward to hearing whether your old machine has the same arrangement since it is much closer in age to my 1968 machine. Many thanks, Davy |
#21
Posted to uk.d-i-y
|
|||
|
|||
Hayter Lawnmower Disc Blade Carrier - how to remove?
I now know how to do this.
Cutter disk is held by a 3/8 UNF bolt (9/16AF or 14mm socket - either fit just as well) and a woodruff key to prevent rotation. Bolt can be very rusty and tends to be worn smooth by contact with hard objects; would be better to replace but is unusual so would need to order. Recommended to jam cutter disc with a mole grip which will jam against a piece of wood against the mower skirt. Retaining bolts needs a lot of torque to get off; is said to be high tensile so head will not shear off. Recommend a six-sided (not usual 12) socket. If this fails then weld a long bar to the nut. The centre of disc is threaded so a 7/16 UNF bolt can be screwed in against the crankshaft end and will force disc off. Need to put a spacer in to prevent threads in crankshaft being damaged. If disk has not been off for a long time then woodruff key is likely to be rusted into the keyway and disk will be difficult to remove. Disk is thin so has only a few threads and these are likely to strip. Some resort to WD40, blow gun and big mallets. Some cut the disk off. If done by a dealer then expect an hour at £30. Examine disk for cracks - if it disintegrated at speed then not funny. If blade bolt holes are elongated then needs a new disk. Whilst disc is off, allows access to oil drain plug so oil can be changed. hope this helps, Davy "Davy" wrote in message om... I am servicing a Hayter Hayterette mower and need to remove the large metal disc that the bladelets are attached to so that I can replace them. I assume I undo the nut in the centre. But how to stop the disc/shaft turning? And does anyone know which way the disc rotates in use - I suspect that the bladelets are on the wrong way round! cheers Davy |
#22
Posted to uk.d-i-y
|
|||
|
|||
Hayter Lawnmower Disc Blade Carrier - how to remove?
"Davy" wrote in message ... And does anyone know which way the disc rotates in use - I suspect that the bladelets are on the wrong way round! Just slowly pull the starter cord while you observe. [Stands by for a safety Nazi to recommend pulling the plug lead off first] Julian. |
#23
Posted to uk.d-i-y
|
|||
|
|||
Hayter Lawnmower Disc Blade Carrier - how to remove?
Davy wrote:
I now know how to do this. Cutter disk is held by a 3/8 UNF bolt (9/16AF or 14mm socket - either fit just as well) and a woodruff key to prevent rotation. Bolt can be very rusty and tends to be worn smooth by contact with hard objects; would be better to replace but is unusual so would need to order. Recommended to jam cutter disc with a mole grip which will jam against a piece of wood against the mower skirt. Retaining bolts needs a lot of torque to get off; is said to be high tensile so head will not shear off. Recommend a six-sided (not usual 12) socket. If this fails then weld a long bar to the nut. The centre of disc is threaded so a 7/16 UNF bolt can be screwed in against the crankshaft end and will force disc off. Need to put a spacer in to prevent threads in crankshaft being damaged. If disk has not been off for a long time then woodruff key is likely to be rusted into the keyway and disk will be difficult to remove. Disk is thin so has only a few threads and these are likely to strip. Some resort to WD40, blow gun and big mallets. Some cut the disk off. If done by a dealer then expect an hour at £30. Examine disk for cracks - if it disintegrated at speed then not funny. If blade bolt holes are elongated then needs a new disk. Whilst disc is off, allows access to oil drain plug so oil can be changed. hope this helps, certainly does mate. Thanks. |
#24
Posted to uk.d-i-y
|
|||
|
|||
Hayter Lawnmower Disc Blade Carrier - how to remove?
On Sun, 27 May 2007 21:23:55 +0100, "Davy"
wrote: "Ian" wrote in message .. . On Sat, 26 May 2007 20:00:39 +0100, "Davy" wrote: Regarding which is the correct bolt to draw the disc off the crank; Looking end on at the head with a flat horizontal there are three lines one pointing to the top flat (12 o'clock), and the other 2 at 120 degree intervals (i.e pointing to about 4 and 8 o'clock). Does this help identify it yes, this is a 'unified screw' bolt; the bolts have three equally-spaced radial markings, the nuts would have three circles. The bolts should also have a figure at the 6 o'clock position which denotes the grade of steel and hence the maximum tightening torque; if this is missing then the bolt is low-grade steel. In which case the maximum torque that should be applied to the bolt is below 65 ft/lb - more than this and you risk damaging the thread or shearing off the head. The closest match to your description is a 7/16 UNF bolt which has 20 tpi. It will not fit a 7/16th BSW thread so my supposition about BSW being used was wrong. But you state that your machine is metric so we would expect a metric thread; a 7/16th diameter bolt equates to 11mm. The nearest common metric sizes are M10 (17tpi) or M12 (14.5 tpi) - so no metric equivalent of this size. Perhapsy Hayter changed the fastenings to metric by 89/90 but not the components? I look forward to hearing whether your old machine has the same arrangement since it is much closer in age to my 1968 machine. Many thanks, Davy Davy Sorry for prolonged delay in replying - I only remembered today that I hadn't replied. My old machine has exactly the same arrangement. I don't think I have ever had the cutter disc off before - if I have it is many years ago, and the last several the m/c has stood outside (shame on me , I know) - retaining bolt came off with little effort. My 'puller' HAS drawn the disc along the shaft but not far enough to actually remove it. Need a longer 'puller' bolt or a hammer! HTH Please reply to group - email address is not monitored Ian |
#25
Posted to uk.d-i-y
|
|||
|
|||
Hayter Lawnmower Disc Blade Carrier - how to remove?
The conclusion of this discussion seems to be:
Cutter disk is held by a 3/8 UNF bolt (9/16AF) and a woodruff key to prevent rotation. Bolt can very rusty and tends to be worn smooth by contact with hard objects; would be better to replace but is unusual so would need to order. Recommended to jam cutter disc with a mole grip which will jam against a piece of wood against the mower skirt. Retaining bolts needs a lot of torque to get off; is said to be high tensile so head will not shear off. Recommend a six-sided (not usual 12) socket. If this fails then weld a bar to the nut. The hole in the centre of the disc is threaded so a 7/16 UNF bolt can be screwed in against the crankshaft end and will force disc off. Need to put a spacer in to prevent threads in crankshaft being damaged and because the bolt is unlikely to be long enough to fully draw off the disk. If disk has not been off for a long time then woodruff key is likely to be rusted into the keyway and disk will be difficult to remove. Disk is thin so has only a few threads and these are likely to strip. Some resort to WD40, blow gun and big mallets. Some cut the disk off. Expect an hour of dealers time at £30. When you get the disk off examine for cracks - if it disintegrated at speed then not funny. If blade bolt holes are elongated then needs a new disk. "Davy" wrote in message om... I am servicing a Hayter Hayterette mower and need to remove the large metal disc that the bladelets are attached to so that I can replace them. I assume I undo the nut in the centre. But how to stop the disc/shaft turning? And does anyone know which way the disc rotates in use - I suspect that the bladelets are on the wrong way round! cheers Davy |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
how to remove the old blade from a used circular saw? | Home Repair | |||
Locking the engine to remove the cutting blade. | UK diy | |||
lawnmower blade... | UK diy | |||
Lawnmower Blade Adapter Removal | Home Repair | |||
Hayter Hawk Mower | UK diy |