# Spin or relief grind



## Ral1121 (Mar 19, 2018)

How do you tell if your reel has a spin grin or relief grind. Are you able to tell from these pics I took of my McLane. My understanding is if it is a spin grind you cannot backlap but if it is relief you can. My reel has gotten real dull from my scalp and a couple cuts. Wanting to know if I can backlap or not?


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## Ware (Jan 28, 2017)

All reels get a spin grind. The relief gets cut after the spin.


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## Mightyquinn (Jan 31, 2017)

I don't see any relief on the blade so my guess would be a spin grind. On a relief grind you would have a secondary bevel on the cutting edge.


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## Ware (Jan 28, 2017)

Here is a good photo (not mine) of a reel with a relief grind - see the bevel on the trailing edge of the reel blade:


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## Ral1121 (Mar 19, 2018)

Since I do not have a relief, backlapping will not help correct?


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## Ral1121 (Mar 19, 2018)

When I look at my reel it is closer to the incorrect relief pic than it is the correct relief pic. It does not have a double beveled edge like the pic posted by ware


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## Ral1121 (Mar 19, 2018)

Here is a better pic so you can see what I see. I guess the diagram is throwing me off because looking at it I have a relief grind.


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## Ware (Jan 28, 2017)

Ral1121 said:


> Since I do not have a relief, backlapping will not help correct?


Seems like I have read that backlapping a reel that does not have a relief cut can cause excessive wear on the bedknife. For a homeowner, that may or may not matter.


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## Ware (Jan 28, 2017)

Ral1121 said:


> Here is a better pic so you can see what I see. I guess the diagram is throwing me off because looking at it I have a relief grind.


It does appear that the blades have a relief cut.

I see some pretty good nicks in the first photos you posted. I would backlap it and see what you can get out of it, but if it doesn't hold an edge very long maybe start thinking about getting a fresh grind.


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## g-man (Jun 15, 2017)

Ware said:


> Ral1121 said:
> 
> 
> > Since I do not have a relief, backlapping will not help correct?
> ...


Without a relief cut, the surface area that contacts the bedknife increases over the designed one. This should cause it to wear faster and more force to turn the reel from the extra friction.

If the reel is worn enough that it no longer has a relief cut then the best course of action is to grind a relief (go back to original design). But if you understand the risks (extra engine force needed and faster wear) then a I don't see why you can't backslap.

From a design stand point, all I see (aka opinion) the relief doing is decreasing the surface area at the tip of the blade. It allows the rest of blade to be thicker, stronger, harder to warp/bend. If you look at a swarman, it was designed without a relief.

I would like to learn more about relief cuts from some of our more reel experienced members.


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## Ware (Jan 28, 2017)

g-man said:


> I would like to learn more about relief cuts from some of our more reel experienced members.


Toro has a pretty good write-up on backlapping and grinding, starting on page 34 of their Reel Mower Basics document.

Regarding relief, they say:



> It is important to understand that Toro reel mowers are designed and manufactured to optimize available power from the engine and hydraulic systems. To help do this, we put a "relief" or back grind on every reel blade to reduce the width of reel blade that contacts the bedknife. This has been proven to reduce power requirements, as well as allow the machine to operate more efficiently. This can be very important, depending on the terrain, type of grass and amount of grass being cut.


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## g-man (Jun 15, 2017)

Thanks for sharing. I read it in the past, but it was good to give it another read. It is interesting that torp says that the relief angle doesn't matter vs jd saying 20 degrees.

On page 40, there is a table with the front angle of the bedknife. It does not list the 1600. Do you know the front angle of your bedknife?


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## Greendoc (Mar 24, 2018)

Ware said:


> Ral1121 said:
> 
> 
> > Since I do not have a relief, backlapping will not help correct?
> ...


Matters a lot. Too much torque required to turn the reel makes chains explode and belts cut. That is after the shaft type parts wear prematurely. Furthermore, that no relief reel must be set with zero contact and that means grass is crushed rather than sheared. That happens. because a homeowner/"landscaper's" reel is nowhere near hard enough to hold a spin grind edge. I have seen zero contact reels with good bedknives and the reel ground down to the spiders. Of course that mower tears up especially Zoysia after the first usage. The golf guys that spin grind do it every week and buy reels every year. But they don't need replacement bedknives very often.


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## mre_man_76 (Aug 4, 2018)

@Mightyquinn, have you needed a relief grind yet and if so where do you recommend? I ask because Eastern Turf does it for $135 but they do not use cut a secondary relief only a single relief. He assured me it is indeed a relief grind and not a spin grind.


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## Mightyquinn (Jan 31, 2017)

mre_man_76 said:


> Mightyquinn, have you needed a relief grind yet and if so where do you recommend? I ask because Eastern Turf does it for $135 but they do not use cut a secondary relief only a single relief. He assured me it is indeed a relief grind and not a spin grind.


I took mine in there earlier this Spring to get the damaged reel ground and asked for a relief grind and they told me that they don't do that so I still had it ground. I wasn't really happy with the results as it looked like they backlapped the crap out of it and the bedknife was worn down to a razors edge. Maybe they have the equipment now to do it correctly. I would give them a shot but just be cautious.


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## mre_man_76 (Aug 4, 2018)

Mightyquinn said:


> mre_man_76 said:
> 
> 
> > Mightyquinn, have you needed a relief grind yet and if so where do you recommend? I ask because Eastern Turf does it for $135 but they do not use cut a secondary relief only a single relief. He assured me it is indeed a relief grind and not a spin grind.
> ...


Airborne!!!
👍🏿👍🏿✌🏿


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## mre_man_76 (Aug 4, 2018)

Mightyquinn said:


> mre_man_76 said:
> 
> 
> > Mightyquinn, have you needed a relief grind yet and if so where do you recommend? I ask because Eastern Turf does it for $135 but they do not use cut a secondary relief only a single relief. He assured me it is indeed a relief grind and not a spin grind.
> ...


Airborne!!!
👍🏿👍🏿👍🏿


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## dfw_pilot (Jan 28, 2017)

TLF is a safe space for both a backlap or a backslap!


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## mre_man_76 (Aug 4, 2018)

dfw_pilot said:


> TLF is a safe space for both a backlap or a backslap!


😂😂😂 well said


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## TNTurf (Mar 20, 2019)

The guy I use only does spin grind. I asked about relief and he just told me he has not seen the need over the 20 plus years he has been maintaining equipment. I can't debate the topic but I can say two months into a spin only, cut every other day, I can cut a single sheet of paper and have only adjusted by one click so far. I have the stuff to backlap but I guess when the time comes I will drop my cutting unit off.


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## Greendoc (Mar 24, 2018)

Spin grind only can work on greensmower with hardened blades and being used on Bermuda that is mowed very often. I do not dispute that at all. Things change when the grass is not going to be mowed as often and the grass is something other than Bermuda or Bent.


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## Reelrollers (Feb 6, 2018)

The only edge cutting the grass is the leading edge of the blade. Whether it's the leading 90 degree edge from a spin grind or the triangle edge you get from a relief. Couple thoughts on both because we do see a lot of greens and homeowner reel mowers at our shop.

Spin Grind: your only option to improve your leading cutting edge is to take it somewhere to get it sharpened. Golf courses do it because it is reasonably easy and quick with a Foley machine or something similar. For a homeowner, they usually have to take it somewhere which is time down and cumbersome.

Relief Grind: still have a leading edge, but opens by opportunity to backlap at home va take to a shop each time to get sharp edge. Someone mentioned the angle of a relief and it absolutely makes a difference. We toy around with different angles and the more aggressive you go, the further grass is thrown to the right side. To keep grass clippings evenly distributed as they exit the reel, the angle does matter.

Something which is very consistent when you read publications... the cut difference (results) between a reel with a spin grind and a relief grind isn't favorable one way or the other.


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## TNTurf (Mar 20, 2019)

Reading my post again, let me say it another way. I asked for a relief grind and would like to be able to backlap at home. The guy that does the work on my reel only does spin. He is about 5 minutes away and returns the cutting unit about a half day later. My other option that I know about will do relief but the wait is about 2 weeks. So, I use the spin only and so far no issues but when the time comes I will have to take it to the guy that does it. The one advantage I have is the flex model. I am only dropping off the cutting unit. It would be nice to have a second to swap back and forth but from what I have seen I can buy another full mower for about the same price. Like I said before, I have nothing to debate and if asked I tell people get a relief in addition to the spin but for me, right now, I dont have the option.


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## Ware (Jan 28, 2017)

Reelrollers said:


> The only edge cutting the grass is the leading edge of the blade. Whether it's the leading 90 degree edge from a spin grind or the triangle edge you get from a relief. Couple thoughts on both because we do see a lot of greens and homeowner reel mowers at our shop.
> 
> Spin Grind: your only option to improve your leading cutting edge is to take it somewhere to get it sharpened. Golf courses do it because it is reasonably easy and quick with a Foley machine or something similar. For a homeowner, they usually have to take it somewhere which is time down and cumbersome.
> 
> ...


Great explanation. I added a link to this post in the sticky thread. :thumbup:


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## Reel_Geek (Sep 15, 2018)

More info to consider...https://www.golfcourseindustry.com/article/gci0412-flat-relief-grinding-equipment/


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## livt0ride (Jan 10, 2021)

Best description and viewing the process for each.

TheGCSAATV
Inside the Shop Episode 9: Reel Grinding
https://www.youtube.com/watch?v=mtPAdQ3i0Zk

John Deere reasons

Reasons for Spin Grinding
-To restore cylindrical shape of reel
-To restore the edge when grass is not being cut (evidenced by streaks)
-To restore edge lost by lack of freq. backlapping
-To restore edge lost by improper reel to bedknife adjustments

Reasons for Relief Grinding
-Reduced blade contact area
-Ensures longer wear life
-Less time is required to backlap
-Reduces pulling and tearing
-Provides an area for backlapping compound


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