What plastic for a mower deck

[PlasmaParticipant @plasma]

Hi all.

I have a well worn steel mower deck which I was going to weld up to get it functional again.

It occurred to me that decks are often made of plastic, thus negating corrosion and painting.

Therefore I began wondering about what kind of plastic, in sheet form, I could use to line the inside of my steel deck to provide a resilient surface over the metal body.

Impact and abrasion resistance are essential but also the ability to cold form sheet material to conform to the shape of the body.

It may be sufficient to just insert a suitable material on areas of the deck that get most wear at the tips of the blade where grit is blasted out at speed.

Any thoughts from our materials boffins would be greatly appreciated.

Plasma

[PlasmaParticipant @plasma]

[Adam MaraParticipant @adammara]

My son has just done the opposite, lined a cracked plastic mower body with steel!

Acrylic can be moulded, I just heat with a hot air gun, but it is breakable. Polycarbonate is pretty tough, but have never tried bending it. At work we made some reverse acrylic printed signs for outdoors, the vandals smashed them! So we made them out of polycarbonate, they could not break thenm so they torched them!

[Neil WyattModerator @neilwyatt]

I used my old push mower to learn stick welding.

Every year was a new O-ring on the carb and another few bits of steel scrap welded to the deck.

When it eventually died it was looking like something out of Mad Max 2.

Neil

[BazParticipant @baz89810]

How about fibreglass, moulds to shape and easy to apply, I think Halfords still sell it.

[Bill PhinnParticipant @billphinn90025]

Posted by Plasma on 05/09/2020 14:52:02:

Therefore I began wondering about what kind of plastic, in sheet form, I could use to line the inside of my steel deck to provide a resilient surface over the metal body.

Plasma

Bear in mind that lining the underside of the deck with anything will have some impact on the flow characteristics of the cut grass around the deck on its way into the box/bag or down onto your lawn. I would weld, personally, or patch, or use a car body filler/JB Weld.

My two Honda HRB 425 mowers are nearly twenty years old and are still going strong. They have polypropylene decks, I believe. These don't corrode, but they can develop full thickness cracks. I repaired a three inch crack of this kind on one of them some time ago with JB Weld. It seems to have done the trick.

[clogsParticipant @clogs]

personally I'd stick with steel……a lot of modern machines now use St/Steel but I guess thay will stress fracture over time…..

the best, long lasting deck we're the cast ally ones made and fitted by HONDA…..

I have one that must be over 25 years old…..

I repair mowers or used to…..

a lot of modern decks use a high carbon steel sheet, thats so the accountants can save 2p and use less metal….

they are absolute rubbish…..they crack easily and seem to rot quicker…..and diff to repair prop….

I found that over time it was better to use nut's and bolts to attach repair panels in the high stress areas, it was the only way to avoid another stress crack……I made mounting brackets that got welded to patches from mild steel…these also got bolted….

at least with the old ones u can go the mad max route like Neil…..hahaha…

most of the mowers I repaired were the ride on sort and in France they are roughly 50% more to buy than the UK….

I used to buy em new when on offer in the UK and sell em on in the spring…..

Oh and just for info a new average ride on mower deck for a Honda was around €1600 plus tax….so they were def worth repairing….a lot of other manufacturers didn't have new decks in the parts list…..

[Michael BriggsParticipant @michaelbriggs82422]

A plastic or any other lining could cause problems if moisture got trapped between the liner and the steel deck.

I have had a Hayter mower with a cast alloy deck for over 25 years or so and still it's going strong. I was warned by a friend with a similar machine that contact with lawn fertiliser can rot the alloy deck, something to avoid….

[Richard S2Participant @richards2]

Can't help with suggestions for plastic coating, as I also agree repairing with steel.

I fully refurbished this 1974 deck (and tractor) back in 2016, sold it in 2018 and is still as good as when I finished it. Mind you, the deck shell thickness is heavy duty-

I can understand the issue if the mowing areas are stoney etc. Maybe braze some brass sheet to the steel where the stones hit?.

Regards.

​

[Robert Atkinson 2Participant @robertatkinson2]

To line the inside of a mower deck I would use high density polyethelene aka HDPE. Some flexibility, good impact and cut resistance. It can be shaped with the application of moderate heat (hot air gun paint stripper). Eben better it is available in small to medium sheets at reasonable cost in the form of kitchen cutting boards. Attach with countersunk fasteners and sikaflex.

 

Robert G8RPI

Edited By Robert Atkinson 2 on 05/09/2020 23:06:28

[HopperParticipant @hopper]

Fibreglass matting then use epoxy resin instead of the usual polyester resin. Boat shops can supply it. Bulletproof. Maybe sandblast the inner deck first for good adhesion.

[PlasmaParticipant @plasma]

Thanks so far for all your input.

Clogs, I seem to have blundered into repairing lawn mowers. The last little shop in the area closed 5 years ago and there is no one doing domestic mowers. I offered to help one guy and its not stopped since.

The mower I am thinking about repairing is a Honda professional machine with heavy weight cast alloy deck. Its fair to say there in only slightly more deck than holes at present. Acid in the grass and not cleaning it has done the damage. I think I will skin the inside with bolt on alloy plates and maybe try some kind of plastic to protect vulnerable areas.

Richards

Thats a great bit of work on the wheelhorse tractor. I have a C-125 which I have just registered for road use. I renovated mine but not to that standard! Excellent work.

I don't think any form of fibreglass would be up to the job, there is just too much wear and vibration.

I can use the Honda deck as a test bed of sorts, trial some of the ideas to see how they fare.

I thought about kydex which can be heat formed but I think its too brittle.

HDPE was my main thought and it can be bought in decent size sheets 5mm thick.

I will carry on and report back if I have any success, or more likely report on what doesn't work lol.

Plasma.

[Henry BrownParticipant @henrybrown95529]

I used to work for a company called Allibert Buckhorn, their main product was very tough "plastic" boxes for the fishing, horticulture and general storage industry. One customer wanted to be able to see into the side of the box so a rectangular piece was cut out and a clear section welded in. I salvaged some of these pieces, about 300mm x 400mm, and they have been very useful. One use was to fit one under each of the rear wheel seat boxes of my Defender, mainly to reduce the clatter of stones but also to protect the underside. They have been under their for over five years and are still fine. Maybe you could source something like this to fabricate an inner for the mower.

[colin hawesParticipant @colinhawes85982]

I repaired the rusted through deck on my mower with fibreglass on the top and inside (like a sandwich) two years ago and it is still excellent now.

[PlasmaParticipant @plasma]

So. After hearing a few ideas from my learned friends, I decided to have the deck shot blasted so I can see what I'm dealing with. There's no substitute for good cleaning of aluminium.

I spoke to a fibreglass specialist who said that would not be a good route to follow on aluminium. Adhesion is not good even with great surface prep, especially if water ingress was a possibility.

Welding is not open to me and the remaining metal is perhaps not solid enough to weld to in some areas.

The best method looks to be making aluminium panels to fit neatly inside the body, then attach them with Sikaflex adhesive. They do a special metal adhesive which remains flexible but has really high strength. Use of their 205 aktivator is recommended.

When the mower comes back from blasting I will make up the necessary panels and have a go at bonding them in place. Outer surface will be filled with plastic padding metal filler just for cosmetic looks and probably painted.

I'll report back in due course.

Plasma

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