OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Walk Behind Lawn Mower Frames Question On Scott Bonnar Cylinder Mowers Reel and blade removal

Hi guys

I'm having trouble with my model 40 Scott Bonner, getting the sprocket off the reel and the screws that hold the blade off. Iv used CRC, heat and a impact driver (on the screws)but they will not budge.
Any tips?
Cheers
Glenn

Hello GRB,

I guess you're referring to the bottom blade (bedknife) screws.
It is unusual that all 4 should not budge using these methods.

First try a centre punch and hit counter-clockwise on each screw head.
[This has worked many times for me]

If that fails, the only safe way will be by carefully drilling the screws out
from the top. The objective is to not damage the threads in the bottom block.

The Model 40 sprocket is screwed onto the reel by a left-hand thread (I think).
A piece of soft wood on the sprocket should budge it.

Hopefully, someone who has worked on the Model 40 will assist here.
We currently have no user or parts lists (unfortunately).

Hope this helps.
------------------------------
JACK.

Hello GRB,

As I have not had any experience with a Model 40 I've to date not chimed in.

I must admit and no disrespect to CyberJack whatsoever as we all have different methods, but the SOP for this type of situation is to put the bed knife into a vice and clamp it hard right in the location of the set screw and with the screw facing upwards, then using a drift of a slightly smaller size as the screw head and then give the screw a solid sharp blow. Don't forget to add some Penetrene or similar. From there you should be able to use the correct size slotted screwdriver and undo it. If all else fails then I would go down the road Cyberjack has suggested. I have watched quite a few fitters use the above method and it works just about everytime.

As far as impact drivers are concerned I've found them to be nothing more than screw head destroyers and they generally maggot the screwdriver receptacle area, thus making the job even harder.

Regarding the sprocket removal, I've learnt something new from Cyberjack.

Hi to GRB, BB and CyberJack,

No disrespect to BB or to CyberJack either, this is a general comment...but the recommended method used here at ODK has been for many years to take the soleplate complete with the bedknife attached to the engineer that will spin-grind the reel and remove the bedknife ( he has the tools and expertise to do it) if it is necessary to replace the bottom blade...which then has to be ground after fitment.

We are talking about a cast iron soleplate here, if you crack it whilst trying to remove the screws...(which has happened) it is irreplaceable...they are no longer available.

A BIG THANKS to BB and CyberJack.
Your advice got the job done.
Again, thank you.
Cheers

And a big thanks to Darryl for your advice to.

Hi GRB,

Just out of interest how did you end up doing it ? also what was the reason behind the actual bottom blade removal ?

Cheers,
BB

Hi BB
I used a smaller drift on all the heads (very hard to hold in the vice as it doesn't have any parallel sides), this loosened one screw. I then used a center punch on the others but let it soak over night in CRC befor I started. It wasn't easy.
Cheers

Hi GRB,

All in all a good result achieved I guess.
Maybe you might get slight discount with your engineer that's going to fit a new blade and then once fitted machine it along with the reel to get a perfect match.

I guess you've really done a lot of work that he could've done, but it's lesson well learnt and we all like to learn don't we.

Cheers,
BB

This seems to me, to be a telling point in favour of handing this job over to a specialist, in most cases.

For someone who is regularly doing these, it's worth their while to build a proper jig to secure and support the soleplate during screw removal.

Support is the key here - unbalanced forces, particularly impacts, cause cast iron to fracture. It's strong in compression, but brittle.

Hi Gadge, and thanks for your valued comment...
It is for the reasons you stated that the ODK team recommend that the removal of bedknife blades be undertaken by the machinist/engineer that does the spin grind.
We have seen cracked soleplates on this forum before, and are expensive to replace....and in some cases are irreplaceable.

No worries Deejay, I just think it's worth pointing out that often special equipment is really required to do a good job, without risking catastrophic damage. And in this field, it's often necessary to have both the abilities and facilities to design and construct your own special tools!

Most folk who haven't had intimate acquaintance [and good instruction/mentoring] with mechanical repair work just aren't aware of these issues.

Hi all,

I might sin bin myself for a while

I hope it won't be for long BB, we rely on you around here. That was especially true when Deejay was out of action, and I thank you for what you've done keeping the SB45 work moving through the site, but equally in normal times you have become a key resource: we can't get by without you.

Hi grumpy, and well said mate....I second that!

BB, many thanks for your efforts here on the forum whilst I was away...you are a truly valued member and your contribution to the various threads have helped many members.
Well done mate.

Hello BB,

What an interesting and telling post this has been.
BB, please report for voluntary duty immediately.
You are the type of specialist ODK needs and values mate.

All very interesting.
--------------------------------
JACK.