OutdoorKing Repair Forum Forums Restoring, Customising and Modifying Reel-Type Mowers How Much Meat Do I Need on SB 45 Reel

Hi
I only just found this great site - and for all these years I thought I was the only SB 45 nutter out here - but happily for me, there seems to be lots of us!!

Anyway - to my question. Due to my, and my long departed Dad's, ignorance on reel set ups, I think I need a new reel and bed knife. The bedknife need is a certainly due to builders dropping a whole box of SS 12mm X 6G screws all over my lawn and I didn't manage to find them all - BUT SB did!!

My reel blades are well worn, so can anyone advise me on how much meat there needs to be left on a 17" SB 45 reel for a regrind to be practical

Hi Blade Butcher, welcome to Outdoorking. Very sad about those screws being stainless, chances are not even Deejay's trick of dragging a magnet around the lawn before mowing, would have worked. (I'm guessing they were austenitic stainless and therefore non-magnetic - all my stainless screws, washers and nuts are.)

You can grind the reel blades down pretty much until they nearly reach the lateral separators before giving up, but what we really need is a picture or two showing the mower for model identification, the reel to assess how much meat is left, and the chains and sprockets just to contemplate how close you are to having problems in that area as well. Then Deejay can get into discussion with you about the overall health of the beast and how to make it nicer.

Tks Grumpy for your "instant reply" and good news on the reel as I have about 8>10mm of blade exposed above support disks / lateral separators.

Will try to post some photos later today / tomorrow - when I get home

My "beast" is a 1968 17" SB 45 (originally purchased by my Dad from Artarmon Mowers). The little (& somewhat gutless for my steep lawns) Kirby Tecumseh was replaced with a 5hp Honda in about 1980 - so those SS screws went straight through the blades.

I hammered the minor bends out of the reel and banged the bedknife back to as straight as I could. Then gave the mower a serious backlap so have managed to remove all but one gouge in the reel and all of them from the bed knife. But as a result of prior wear and the vigorous back lap - the leading edge of my bed knife is down to about 1.5>2 mm thickness
Chains and sprockets are all good - have just had the driveline disassembled to replaced the drive drum bearings

Hi again Grumpy,
OK, as requested - Here are some "happy snaps" of my SB 45, its ID plate and its reel and bedknife -
Any thoughts / comments on reel / bedknife remaining life

Congratulations on the GX140 engine - I think a GX120 would have been more than adequate to do the job, but they are both nice engines. I don't recall the output shaft sizes - you may have had to get the 140 to get a 3/4" output shaft so you wouldn't need to replace the engine-side half of the clutch (the Kirby has a 3/4" shaft and I think the GX120 is 5/8" unless you get a variant version on special order). As expected for such an early machine, you have a one piece engine deck, which is perhaps just as well since the mower now has double the power Scott Bonnar thought it should have. (The later twin rail version seems prone to cracking the front rail at the inboard engine mounting bolt.)

I'll leave Deejay to talk about interesting features like the strips you've riveted onto the roller, presumably to help get up your hills, and how thick is thick enough for a bedknife. The reel looks to me as if it still has well over half its total life in front of it, but that is Deejay's territory.

Tks Grumpy for your reply and comments and look forward to any additional thoughts Deejay has on my reel / blade.

As I mentioned in the initial post - I have managed to "backlap" out all but one small gouge in the reel blades and all of them from the bedknife - even if it took nearly an hour and 1/3 of a tub a lapping compound - Grrrrrrr - I might put the remaining 2/3 into those builders' coffee cups

I put the GX 140 on with my Dad back in 1980. I don't recall if we even thought about anything less than 5HP as the little Kirby just wasn't up to the task of buffalo grass and steep grades. But the 5HP Honda has no trouble with the grades and has the buffalo trembling in its tracks.

Putting the engine on was a bit of a fiddle - had to mark out new engine mount holes and weld some flat bar under the deck to match. Then move the clutch outboard so the engine would sit inboard of the frame (we have elevated garden walls - so the engine had to sit entirely inside the frame). The fiddliest job was cutting the clutch output shaft and milling a new keyway in to accomodate the 2"+ we took off to allow the engine to fit. I have a lathe but NO MILL - so had to mill the shaft on the lathe with a simple milling vyce set on the tool post holder and an end mill mounted in the 3 jaw chuck - must have taken me about an hour to set the shaft up to exact centre height and square with the chuck so I could mill the keyway.

Yes - the ribs on the rear roller were put on to keep traction without skidding up the grades. My old Dad did that many years ago - I still marvel at his patience. He didn't dismantle the rollers and cut, drilled and counted-sunk all those little strips of 3mm x 12mm flat bar - then drilled and tapped all the holes in the roller and screwed the bars on with some Loctite. He was retired at the time - but nonetheless - it must have taken him days.

Hi Blade Butcher, and a warm welcome to the OutdoorKing forum. It's always great to welcome another Scott Bonnar Model 45 owner.

Well, now down to business..... You have certainly got the age right for your machine...it is a '68 model, the first of the line, solid engine deck, alloy end caps and grass deflector screws rather than black plastic knobs and will have horizontal screws in the chain case cover rather than the vertical ones of the later model.

There have been some 'tenants improvements'.... I can see...the engine has been moved to the left (viewing from the front) and the output shaft has been shortened and also the cutter clutch actuating assembly has been moved to suit. Why, I do not know....but I can see the original holes in the engine deck for the original placement. I suspect it was to fit the larger Honda engine. (My Scotty has the Honda G100 2.5HP side valve engine and is perfect for my lawns)

To the reel and bed knife...the reel, in my opinion, would benefit from a spin-grind (which only removes minimal amount of metal). This would remove any imperfections and square up the reel; backlapping can't do that.
A new set of reel bearings will not go astray, (they are cheap) as even if they are slightly worn, you will waste the effort spin-grinding and the adjustment (reel to bed-knife) clearance will be out of whack.

What concerns me most is the bed-knife; it is not original, and has been re-drilled to suit the soleplate....In fact if you look at your pics closely....you can see the original holes in front of the bed-knife screws. You can see also the the bed-knife has curled up at both ends. It is shot!

Here are my recommendations:
(1) Remove the cylinder reel and soleplate, complete with the shot bed-knife still attached using the guide Joe and I made HERE and take both to the engineers workshop.

He will then spin-grind the reel and supply you with a new bed-knife blade and new screws to suit, which will be the same as the original Scotty bedknife.

(2)Pick-up and install the new reel bearings.
(3) Re-install the cylinder reel and soleplate/new bed-knife and adjust the clearance using our guide HERE.
Please let us know how you get on.
Once again, to the forum.

I hadn't noticed that you have moved the engine inboard, but now that you mention it, you certainly have, about as far as possible in fact. That is a very customised SB45.

I'm not fond of major backlapping, since the result is likely to be some matching waves in reel and bedknife, so when you finally get it ground, quite a bit more metal needs to be taken off both components to get them back to straight. However, you aren't the first backlapping enthusiast to be here on Outdoorking, it certainly has its adherents.

Hi Blade Butcher, you must of been posting as I was typing.
Well we're all on the same page now. I didn't comment on the rear roller; it is self explanatory when you mentioned the hilly terrain you're mowing.

Tks Deejay - you inputs are much appreciated and will be arranging for a new bedknife and regrind of both bedknife and reel very shortly - also agree bearings "and grease" are the cheapest things that can go into a SB - so will be getting newies as well

I figured the bedknife was beyond its use by date and has suffered from both a very recent & very vigorous backlap courtesy of my clumsy builders and years of negotiating my concrete kerbing.

You are almost right on the origin of the bed knife!. It is an original SB but when it wore out some years back and I was having trouble locating a replacement - I marked out the hole pattern on the reverse side - redrilled and C/Sed the screw holes and had it surface-ground - so what you see is a reversed / recycled bedknife.

Yes - the engine has been moved to accomodate the 5HP Honda as the orginal Kirby Tecumseh just wasn't up to my grades and buffalo grass. My "old Dad" & I tolerated the "little Kirby" for years and even gave it a rebore, new piston & rings - but by 1980 enough was enough - so on went the Honda - Maybe overkill @ 5HP - but whilst there are all kinds of "powers" - eg willpower, thought-power, people-power etc - for a Mining Engineer there is only one kind of power - that's HORSEPOWER!

Here's a happy snap of my other "toy" that I have been known to, very occassionaly, cut grass with - though not by choice - it's just that some more remote coutry strips are grass and they aren't mown that regularly

Deejay - they are great videos - and I have certainly learnt something about setting up / adjusting the SB reel - in the past I have always had solid contact with the bedknife which probably explains why I wear out bedknife blades and knock my reel about - so from now on they blades will be reinstalled with the minute clearance you showed in the video. Would a 1 thou gap set with a feeler gauge be OK??

As suggested - I chased up spin grinder and bedknife shops. The guy I have used in the past, and who does lots of golf green and bowling green mower reels / blades, uses a "full blown" centre grinder with a 500mm dia grinding wheel. He has always been very good BUT is so busy that he can't do mine till the New Year.

I found another shop who can do my reel and bedknife in the next couple of weeks - but this guy does "relief grinds" on the cylinder reel and insists that the reel bearing shafts be knurled before fitting new bearings. I noticed that Deejays reel bearings were a snug but sliding fit on the reel, as are mine -so I am not sure about this guy's plan to knurl the reel bearing shaft and know nothing about the idea of "relief grinding" the reel

Do you guys have any thoughts / comments on the plan to knurl the reel shaft and the idea of relief grinding the reel.

Hi Blade Butcher, please take my advice and don't let the second guy near your reel under any circumstance.
Tell him 'He's Dreamin!'
Knurl the shaft indeed....

Just contact your local Bowling Clubs and talk to the greenskeepers about who does their cylinder reels and bed-knives. Find one that can do a standard grind for you.
Just a straight spin-grind is all that is required; a serviceable bed-knife fabricated and ground and faced to suit.

Here are some facts for you to ponder:

Myth: You must have contact between cylinder and bedknife.

Fact: �You do not need contact between the reel and bedknife to cut turf grass. Contact between the reel and bedknife will generate heat which will have many effects on not only the turf grass, but also on the traction unit. The heat generated between the reel and bedknife will tinge the leaf blade. Also that heat can cause the bedknife to expand which will tighten the cutting unit up even more. The tighter the reel - bedknife contact, the more strain this puts on the traction unit which can cause hydraulic hose failure and premature failure of the hydraulic system�.

Contact between cylinder and bedknife causes drag requiring greater effort to turn the reel and in turn this greater effort has an adverse effect on drivelines and engines. This drag also leads to rapid wear and loss of sharp edges, as well as a poor quality of cut. With contact you have the undesirable �scissor� action instead of the desired �scything� action. It is the scissor action which damages the turf plant and can prolong the healing process.

Myth: New bed-knives are �true� and don�t require grinding.

Fact: �New bed-knives are certainly not true coming from the factory. Every bedknife that gets installed on a bed bar (sole-plate) needs to be ground properly in order to achieve a consistent quality of cut. The bedknife is the single most important factor in achieving a great quality of cut. The bedknife�s job is to position the grass before the reel blade cuts it. Depending on where the position is will depend on how clean and consistent your turfs after cut appearance will look.

Bedknives will take the shape of the existing bed bar once tightened. By grinding the bed knife properly it will give you a smooth surface that you will then align to a reel that has been ground to a true cylinder. Once this is complete you will have 2 perfectly aligned surfaces that can achieve the quality of cut that everyone is looking for.
PS. I love your other toy....

Tks Deejay - your advice is much appreciated.

On that knurling question - I am only a retired Mining Engineer - and at best, a very an amateur machinist - BUT for the life of me I could not see how knurling a reel shaft bearing seats would do anything but throw the the whole thing out of alingment - afterall, as I understand things, there is no precision in a knurled finish - so your adice to steer clear of the 2nd guy is well received.

So as suggested - will just have to wait till the New Year for my original guy who does a standard (not relief) grind (with the 500+mm wheeled centre grinder) to find a bit of free time to do my reel and get a new bedkife set up & surface and end ground. I guess if the guy is flat out till the New Year with golf green and bowling green gear - he must know what he's doing. In the meantime I will get a pair of sealed bearings to suit the reel, so all will be ready to go in the New Year

Deejay - I watched your videos a couple of times and learnt heaps - but I still need a little coaching on just how close is close enough for the gap between the reel and bedknife. I understand they shouldn't touch - but would say 1-2 thou gap (that I can set up with a feeler guage) be OK, or should it be more or less?? This last setup bit is still a bit of a "Black Art" to me.

P/S On the few occasions I have cut grass with my "other toy" - it has always stired up a swarm of grass hoppers - and I can tell you with absolute authority - Grass Hopper guts are made of SUPER GLUE!!!! and are insoluable even to truck wash!!!

As to measuring the clearance on setting the reel to bedknife, in my very little experence compared to others I do it by feel, find a point where it barely touches then back it off 1/8 of a turn until you have nil contact.

There is a guy on ebay showing photos with a releif grind, apart from taking a rediculous amount of metal off the reel I cannot see any other point of it, the showed a photo of each edge ground to a point.

There is a sort of point to relief grinding, Joe. By having only the leading edge of the reel blades close to the bedknife, the remainder of each blade has so much clearance that there is no real possibility of smearing the end of the grass leaves, as more or less inevitably happens with a conventional grind when the leading edge is even microscopically rounded. To see what I mean, just try using a lathe cutting tool with no clearance angle. Cutting pressures become enormous, horsepower required goes way up, the tool overheats, the chip looks woeful, and the surface finish on the machined surface is awful. There are two important problems with relief grinding, however. First, the tiniest amount of leading-edge wear (grass is rather abrasive, so there always is leading-edge wear) increases the blade to bedknife clearance and changes the whole cutting setup. Second, the reel blades are consumed more quickly with relief grinding, due to requiring more frequent sharpening. (There is a third "disadvantage" that I don't personally care about: you can't backlap a relief-ground reel, since that would immediately remove the relief-ground clearance on the blades. I don't care about that because I disapprove of backlapping, which is likely to lead to a wavy blade and bedknife.)

I don't really want to enter debate on this issue as we've all been through it before, but here is my two-bobs worth.

I have discussed this issue with many greenskeepers, and none of them advocate 'relief grinding'. However, their machines have the capability of being able to reverse the reel by turning it over 180 degrees and re-installing; whereas the 'back' edge now becomes the front edge.
With a Scotty Model 45, this is impossible, because of the reel design.
Any procedure that removes a lot of metal from a Scotty reel in my opinion is to be avoided at all costs.....at almost $400+ for a replacement, it is more than the cost of a second hand mower in most cases.
I rest my case.

Tks Guys - your collected wisdom and advice is priceless & very much appreciated.

Joe - OK will try the "back off by 1/8 turn method" and see how I go.

Joe, Grumpy & Deejay - As I mentioned earlier in my thread - I know nothing about relief grinds - so your inputs, viz:
"..taking a rediculous amount of metal off the reel...",
"...the reel blades are consumed more quickly with relief grinding.." &
"...I have discussed this issue with many greenskeepers, and none of them advocate 'relief grinding'..."
are all very good points on relief grinds - so I will be avoiding that too.

P/S Just got a note from Council telling me that they just about to dig up all my nature strip for some drainage work. Last time they did something like that they left the grass full of what they called "crusher dust" - but what it really was, was a sort of fine road base full of 3/16 gravel - I must have done something to upset the "Lawn Gods"

May be a good idea to let them know that you mow with a cylinder mower and that the ' fine road base full of 3/16 gravel' will cause damage to your machine.They may just replace with soil, and all will be well. Also maybe the promise of a couple of 'coldies' at the end of the work sometimes works wonders......
Best of luck with it...

Deejay - Tks - a damned good idea.

The "crusher dust" seems to be used mostly to bed & top the pipes when they lay / replace them; but gets spilt all over the place as the put in the trench with a loader bucket.

But you are a genius - I think I will give them a 6 pack at the start, on the condition they don't spill their "rubbish" in my grass coupled with an offer another 6 pack if they live up to their side of the deal and if they get some proper topsoil to cover the trenching wounds.

Afterall a couple of 6 packs is less than 1/2 the price of a new bedknife!! and I have nothing to lose.

Deejay, Grumpy & Joe.

OK - did the "just contact then back off 1/8 turn thing" with my blade adjust. The reel & bedblade don't touch at all and whilst it felt a bit wierd (given my lifetime of incorrectly adjusting the blades so they made contact with the bedkbnife) - it worked a treat. Less noise and a much cleaner cut even on my tough buffalo grass. Tks Guys - your advise was spot on and much apprecieted.



P/S Look what Council has just delivered to my SB45 for Xmas!



Somehow I think that I am going to need more than a couple of 6 packs to get around this lot.


Anyway - my 1st task on Monday is to see if I can bribe these guys to move the pipe and concrete pits onto the road so I can at least give the nature strip a mow / tidy-up before Santa comes.

Somehow - from the look of the pipes and pits - I don't think there will be much left of my nature strip in the New Year - and damn-it I just recently spread about 1/2 bag of "stinky pellet" lawn food on to that grass.

As I said - I have done something bad to upset the "Lawn Gods"