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TOPIC: using Hummel to fix waving floor refinish do-over

using Hummel to fix waving floor refinish do-over 01 Jun 2016 16:19 #18071

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Hi Everyone,

We had 650sqft of white oak floors refinished last week by a reputable local flooring company and when we came home Saturday there was very noticible wave throughout the floors, visible cross-grain swirl marks and debris stuck in the Bona HD satin (they did 3 coats).

I started reading a lot of flooring posts and came to suspect the wave was caused by their Hummel. I also read that the best way to definitively correct the issue was to resand and use a Trio (or possibly a 3Ds or Multidrive) to correct the wave.

The owner came out on the morning of the next business day and agreed that it needed to be redone. He apologized and said they would cancel their next scheduled job to start redoing the floor this week. When I asked if he had a Trio or could access one to fix it, he said he could but that the Trio leaves a different type of scratch pattern in the floor that could be problematic. This didn't sound like a plausible reason not to use one to me because I thought correct progression of grit would mitigate scratch pattern issues. Anyway, he defended his Hummel and said he would take it to the shop to get it checked out first but he seemed resolved that it be used again for the re-do.

His crew came out today and also defended the Hummel and said they take great care of it with transport and storage when I mentioned possible issues like the wheels or flat spots on the drum and they started resanding.

They finished for the day and have left the Hummel sitting in our dining room, on its wheels with a sanding belt on it. From what I read, this is not proper overnight storage and inviting problems Iike wave/chatter due to wheel and drum issues.

Maybe I'm just being paranoid but I'm very worried the rework is going to leave us with another wavy floor due to this. Is it a really bad thing that the Hummel is sitting in this state? I imagine they probably leave it like that on other job sites as well and this isn't the first time it has sat all night on its wheels.

The crew don't seem disposed to listen to me about my concerns because I'm just a woman reading stuff online and don't sand floors for a living. I'd like to hear from people who do refinishing professionally about whether this contractor is doing things competently. I really don't want my floors refinished a third time!!

Thanks for any input or advice.
Last Edit: 01 Jun 2016 16:27 by SnowTurtle. Reason: Delete extra pic

using Hummel to fix waving floor refinish do-over 02 Jun 2016 15:52 #18085

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Leaving the sander on the job is done by 100,000 floor sanders every day. His Hummel looks fairly new or very well kept IMO. If he is willing to redo the job and take the responsibility then let him do his thing. I'm sure he'll come through for you.
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using Hummel to fix waving floor refinish do-over 02 Jun 2016 17:57 #18093

So did he service the Hummel before redoing your floor? If not it will still leave waves.

My Hummel only sits on the wheels when it is sanding. In the van it rests on it's frame on a platform. If left on jobsite I tilt it back so the weight is not on the wheels.

You are correct that a floor belt sander should not be stored with a sanding belt on it . That's very basic knowledge and any wood flooring pro should know that.
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using Hummel to fix waving floor refinish do-over 02 Jun 2016 20:06 #18097

He said he was going to have the shop look it over, so I can't verify whether it was done. He has 3 Hummels and this is the new one.

The owner said they will be hardplating the floor tomorrow with a 16" disk and doing two full passes with it and possibly staining tomorrow -- but maybe the following day if the hardplate takes longer than expected. I also asked them to show me the stain samples water popped (they call it "tacked") because I read that helps soften scratch patterns.

So given the decision to hardplate maybe the state of the Hummel won't matter as much...?
Last Edit: 02 Jun 2016 20:14 by SnowTurtle. Reason: Punctuation

using Hummel to fix waving floor refinish do-over 02 Jun 2016 20:14 #18098

Hard plating will not take out waves. It takes out chatter but it doesn't sound like chatter is the problem.
How dark is the floor going to be stained? Hard plating leaves swirls in the floor. If your Hummel is set up and running correctly there is no need to hard plate.
IMO hard plating is a waste of time and causes more trouble then its worth. I worked for a guy 25 years ago that hard plated every floor...it was because his drum sander was a piece of crap
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using Hummel to fix waving floor refinish do-over 02 Jun 2016 23:15 #18100

The stain color we picked was not very dark and called "Medium Brown."

I'm pretty sure we had waves rather than chatter but I'm posting the pics I took of the first refinish so you can see. The green hue is from all the trees outside the windows. I think you can also see some grain dishout in the photos and I've been concerned that it could be made worse from the Hummel and hardplating too.

It was difficult to photograph the wave/ripple, much easier to see in person.

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Last Edit: 02 Jun 2016 23:23 by SnowTurtle. Reason: Add sentence

using Hummel to fix waving floor refinish do-over 03 Jun 2016 08:47 #18101

  • Greg Warren
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I always leave my hummel sitting on soft rubber mats and the drum belts disengaged when left on the job. Off the job it sits on a Hummel dolly. The wheels could have a flat spot on them as well as a drum that has a flat spot from overnight drum belt pressure sitting on a hard surface. These machines really have to be cared for religiously. Time spent hard platting will help.
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using Hummel to fix waving floor refinish do-over 03 Jun 2016 19:06 #18109

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I run a super 8 belt and leave paper on all the time , it does sit on a special carrier in the van but I always leave it on job when I'm not finished. My floors have absolutely no issues. I think the Hummel has some obvious flaws. I own a Hummel as my back up , but over the years I've heard time and time again about problems with the Hummel. Don't get me wrong, it sands just as good as my 2005 super 8, but my super doesn't have these issues. I replaced my roller for the 1st time 2 years ago. My mechanic said that my machine has the best roller . Never replaced a capacitor.
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using Hummel to fix waving floor refinish do-over 05 Jun 2016 13:13 #18114

It doesn't make sense that a defect in a wheel or roller would cause a line to go across many boards in a pattern that is wider than the 8" path of the belt/drum. The wave can be effectively managed away by running the Hummel from left to right and at a slight angle (10 to 15 degrees) to the axis of the floor boards. You should also be meticulous in keeping the floor free of any debris because every little thing you run over causes the machine to hop and changes the path of the sandpaper belt.

A hard plate is a full sized (16" - 17") sandpaper holder that fits on the buffer. Used properly with the correct sequence of grits it will grind the surface flat and smooth. Many of the newer multi-disc machines can substitute for the hard plate, but it is extremely important that the operator looks at the floor as he/she runs the machines. Wood floor sanding machines do not work like lawn mowers. Screen discs will not remove wave and if they are run with a softer drive pad will sand out the soft grain in ring porous hardwoods like oak, ash, or hickory.
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using Hummel to fix waving floor refinish do-over 06 Jun 2016 07:46 #18118

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I once refinished a floor I had previously finished new. Santos Mahogany. I had let some latex filler slowly build up on one of the side wheels. Just enough to create a wave pattern due to the out of round nature of that wheel. The Hummel will wave unless all aspects of the roundness of the machine's parts are true. Stay away from after market Hummel drums made by other than EOM. I have found them over the years to need dressing to square them up. The EOM works true out of the box.
It is possible that this defect was already in the floor before sanding and the sanding accentuated it enough for it to show up with new finish applied.
Last Edit: 06 Jun 2016 07:49 by Greg Warren.
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using Hummel to fix waving floor refinish do-over 06 Jun 2016 15:31 #18132

I accidentally posted a new thread in the wrong forum (I think) and I'm not sure how to move it.

Anyway the update is that they just applied the first coat of Bona this afternoon and I can see a wave/ripple in the floor even at this point. I am at a loss as to what I should do. I want to just tell them not to waste any more time applying the rest of the Bona and to give me my money back so I can find a company who can do a proper job.

Here is what it looks like now:

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They also didn't sand and refinish the bullnose of my floor where it borders the sunken living room. They sanded up to it and just left the old finish on the rounded edge.

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Last Edit: 06 Jun 2016 17:37 by SnowTurtle.

using Hummel to fix waving floor refinish do-over 06 Jun 2016 15:42 #18133

The floor will only look worse with more coats applied. Either they didn't cross cut to get the previous waves out or their sander never got fixed.
From the pictures it looks worse now then when done the 1st time and there's only one coat on it.

Probably be best to get your $ back and find someone else.
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using Hummel to fix waving floor refinish do-over 06 Jun 2016 16:17 #18134

"It is possible that this defect was already in the floor before sanding and the sanding accentuated it enough for it to show up with new finish applied."

Greg, there was no visible ripple in the floor before we had them refinish it, so if it were pre-existing wouldn't we have seen it? It also had a significantly shiner polyurethane applied before. I'm pretty sure it was an oil-based semi-gloss before and we are having them use Bona Traffic HD in satin.
Last Edit: 06 Jun 2016 16:19 by SnowTurtle.

using Hummel to fix waving floor refinish do-over 06 Jun 2016 16:27 #18135

Thanks, smokersteve. That's what I feared. What a complete pain.
Last Edit: 06 Jun 2016 16:28 by SnowTurtle.

using Hummel to fix waving floor refinish do-over 10 Jun 2016 13:40 #18200

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Ok so we've all had our own experiences and like i said there are numerous potential causes for waves but the Hummel, coming from a Hummel dealer and drum reconditioner, is caused by the can we call it, the belt release lever being left in the tension position, not the cut aggression setting on the right side of the machine. I'm sure your all familiar with materials expanding when hot? Then when it cools it shrinks. Now imagine there's extra tension on a specific spot and allowed to cool from hot to cool and you get a flat spspotThats what causes what's called the Hummel wave. Can't speak to the construction of the super eight as its been 30 years since I moved on from it to my 2 Hummels.Btw, notice to everyone, successive straight cuts will cause ripples and grain tearout on plainsawn cuts like in these photos. Never do a straight cut but on final cut. Learned that 25 yrs ago on a 8' southern yellow pine floor. Between not angle cutting the over wood, new floor, and the very soft grain there were ripples everywmmels.The butts roll over and makewhat looks like big drop marks. I now cut every new floor on a 30-40 degree angle to flatten out the overwood. FirSt I get the floor flat and then I do 2,40 then 60 grit disc cuts in the field. If you don't have some kind of buffer attachment or trio to go over the floor after your big machine then in my opinion your on the back end of the curve brothers. Those that have them know what I mean, as you simply can't do a comparable job by just screening with a buffer. Bla, bla that's still a bad job whether its the Hummel wave or some other problem. Using the same guy with the same equip is gonna yield the same outcome. Hire someone with a trio, ufo, Clarke DA, or overpriced Bona machine and get the floor you thought you paid for. Here's a suggestion, contact some pro's and find out what there using for equip and post those options so we, as a group can weigh in before you get another bad job. Just saying.
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using Hummel to fix waving floor refinish do-over 13 Jun 2016 22:44 #18262

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Those waves look like they come from an unstable floor. If the floor is not nailed as securely as it should be, it moves back and forth as the sanding belt on the 300 pound Hummel pulls the wood. This should be sanded with the Trio or a Bona multi-disk. The other contractor is correct. about the different scratch pattern. It shouldn't be that obvious with a dark color. If these were chatter marks from a defective sander, the pattern would not extend out to the sides like that. We have Hummels. They are great machines when properly maintained.
LMA

using Hummel to fix waving floor refinish do-over 17 Jun 2016 09:57 #18299

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Brickman, I have seen a wave ditch, drop mark expand across the grain. If you ever get a chance to look at a wide width floor that was only sanded once, after install, and they didn't angle cut the overwood at the butts, just did straight cuts,depending on how bad the mill there can be a valley on either side of the butt a board or 2 wide as the butt rolls over and the sander continues to follow with each successive cut. The same can happen if you don't start with an aggressive enough or old belt when roughing wide widths and you get soft grain tearout and that continues with each successive cut. In my opinion it can be counterproductive to go too fine on wide plainsawn flooring as you're going to increase the likelihood of soft grain dish or tearout. . You can definitely see some of the worst ripples in these pics are where there's wide bands of soft grain on this plainsawn oak and the floors being loose can accentuate the waves/ripples for that reason I put my Hummel away after a30 degree 50 grit cut and hard plate to finish with my UFO 40 then 60 grit disc and 80 screen. I only use a quarter inch driver pad so there's no give and I get flat and almost no tearout and the result is a very flat floor. Most of the ripples in this floor can be explanded by leaving the sanding belt on and too many straight cuts. This is assuming that there's no mechanical fault. Operator error can explain much of what I see in these pics.
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using Hummel to fix waving floor refinish do-over 22 Jun 2016 10:16 #18353

Snowturtle,

Any updates? Did you find someone else to fix your floor?

using Hummel to fix waving floor refinish do-over 31 Mar 2021 01:40 #21029

15 years using Hummel and Trio...Only time I have experienced these waves is when I have had to separate Hummel to get upstairs...if tighten the V belt if TOO TIGHT will leave wave marks..
Last Edit: 31 Mar 2021 01:41 by Gixerags750.
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