I have only noticed it on the x-carriage and to a lesser extent, the y axis. The spindle has been fine, other than I had to increase the stepper motor current to get it to travel all the way.
No resolve yet over here. However, I did find that any debris(mdf), on the rails or wheels will amplify the effect. There is also a very slightly discernable ripple in the material being cut in that particular area of the “speed bumps”.
The thickness of the center washer can vary by how much the center rib on the V wheels is out of spec. Look here for what I found when I measured all the wheels that came with my machine…
Most users of X-Carve machines will not have the measuring tools or metal lathe to take measurement of each wheel and determine the exact thickness of the spacer washer. That being the case the use of a fiber washer that has a little give to it is a good choice for replacing the metal washers in wheels that have movement.
Hope this helps
@DavidSohlstrom So I am just trying to understand the problem I need to fix… Is it that the washers are too small and the bearings are only sitting on the top ring of the wheel or that the washers are too large and the bearings are not touching at the top ring of the wheels? I think you are saying its the later, but I cannot move the wheel back and forth so I am not sure if the bumps I am expecting are caused by faulty washers yet. I suppose I will have to take everything apart and see if there is play in them as it does not feel like it while on the rails.
There are 2 conditions that happen here. There is also 1 ideal condition. First the ridge in the center of the wheel is to thick 1mm+ and the washer is thinner that the ridge. Here is what happens when you bolt up a wheel to the machine. The thick ridge causes the outer races of the bearing to be held to far apart and when the bolt is tightened the inter races of the bearings are squeezed and put into a thrust condition. The bearings they are using are not made to be in a thrust condition. This causes the balls in the bearing to ride on the outside of the outer race and on the inside of the inter race.
Next condition is where the ridge in the center of the wheel is to thin and the spacer washers are to think. This means that when the wheels are bolted to the machine the wheel can slide back and forth on the bearings. This is not good because the machine does not track correctly and you will see this in the parts you make.
The third condition is the one we are looking for. this is where the ridge in the center of the wheel is at spec of 1mm and the spacer washer is at spec at 1mm. This does not squeeze the bearing as in the first case and does not let the wheel slide back and forth on the bearings in the second condition.
As I noted in another thread where I measured all of the wheels I received and all the bearings and all of the spacers There was a big variance in the thickness of the center ridge in the wheels. The greater majority of the spacer washers were thicker than 1mm. The OD of all of the bearings was less than 16mm ranging from 15.99 to 15.97mm.
The 90 degree angle on all the wheels was less than 90 degrees causing the wheels to ride on the MS at the very OD of the V groove.
What does all of this mean. If you work to a tolerance of + or - 1/32 inch then not a darn thing. If you want to work to a tolerance of + or - .003" as the machine specs say it should be able to do then you could run into problems.
Hope all of this helps
I’m not scientist, Just one old mechanical engineer. I don’t know how to turn simple problems into science project.
Here is how I solved my problem,
Purchased 10 packs. Makes 20.
Moving/Bumping/humbling problems gone.
This is the washer fits perfectly. Keep it simple.
Hi. I wanted just to say that i have exact the same issue with my x-carve 1000 which i had purchased just a few weeks ago. I see the effect on all of the three axis. On the main axis with spindle however it is way more clear than the other two.
I have not finished assembling yet. Is this phenomena something i should worry about? Is there any official support for this problem from inventables or we are on our own…?
If you haven’t assemble yet, go buy thinner washers, pop one side bearing off on the V-Wheels and replace with those thick flat washers. You will not be sorry. I tried about 4 different washers until I found this.
@DavidSohlstrom: well-explained…I don’t have any of my hardware yet (but UPS claims to have it in-hand!) but this helps to solidify my understanding of the issue. Seems like micro differences in washer thickness can be addressed with simple sanding.
The spacers that come with the V Wheels are 5mm ID 10mm OD and are speced at 1mm thick in Stainless steel. Reducing there thickness can be done just time consuming and if you do not have a way to measure both the spacer and the ridge in the middle of the V wheel it is a hit and miss exercise.
Alan’s use of fiber washers in various thicknesses is a very good way to adjust the spacing of the bearings in the V wheels.
Seeing others now having this problem I wonder if a change was made in the washers, bearings or V-Wheels recently…
@DavidSohlstrom Thanks for all the info, but prob like many others in this thread I do not have access to all the tools you have. I just expected that Inventables had tested or proven this system to work. Did you provide your findings to them and if so do they have any thoughts of what changed in their supply chain?
@MohammadS_Sadri No official word yet, I guess no one from Inventables has read this thread yet. I suppose we’ll all have to email them and see if they have heard of the issue. I figured I would wait for a bit for someone to respond but does not seem to be the case. I am at the same stage as you, still doing assembly. Don’t want to go much further as I expect I will have to disassemble a bit to fix it. I am worried because I can actually see the spindle mount moving up and down and that will surly show up in the work.
Is it possible for you to put a link where we can buy the Washers?
I am an electrical engineer with absolutely zero knowledge of mechanics.
Also I live in Germany, and here I think the naming convention differs from states, so would you please tell me the exact size of the washer? e.g. 4mmX3mmX… since when I search for the item in ebay.com I find something, but in ebay.de I get completely lost.
It’s 0.032" thick makes about 0.8128 mm. Outside diameter is 9.5 mm. Inside hole diameter 5.30 mm.
I purchased from local Home Depot but I think this is the link.
I did some testing today.
Took my carrage and installed 8 random wheel on my new bearings with 8 random 1mm spacers and put the 2 1m MS in. I tightened the eccentric nuts fairly tight on the MS.
When I moved the MS back and forth one was nice and smooth and the other had a tick in one bearing.
I checked the distance between the MS with just a steel rule. With the MS centered on the carrage I had a 3/16" gap on both sides of the carrage.
Here is where it gets interesting. Looking at the ends of the MS the MS with the logo on it was about 1/32 higher that the other MS. Changed the top wheel on that side with a different one. Both ends now at the same level.
More fun stuff. I slid both MS all the way to the left. When looking at the ends of the MS I could see that the gap was bigger. It was now 1/4". Checked the other end and it is under 3/16.
I looked back at the data I had recorded when I measured the wheels. There are about half of the wheels that the center ridge is not centered on the wheel.
What I think is happening here is when I picked 8 wheels I did not pay any attention if the ridge was centered in the wheel and did not make sure that I mounted the wheels with the offset on the same side.
This is what gave me the difference when I slid the MS to one end of the travel.
What does this mean if I were to install the MS on the end plates and set the distance the same on both ends. This is going to put the wheels into additional binding.
All of this adds up to possible problems that people are seeing in there machines.
Hope this helps
The washers that came inside my v-wheels all had a burr on one side from being made by being punched out. I noticed that this burr was running against the bearing seals and causing friction, so I removed the seals of all the bearings on the inside. Theoretically, this shouldn’t cause any problems being unsealed, and is easier than replacing all of the washers. I’m still having other issues that seem as if the wheels aren’t perfectly true and centered, causing very noticeable wobble in the plane of movement. I don’t see any way of fixing that problem so I ordered new v-wheel assemblies on eBay from a seller in Hong Kong. I won’t be able to give an update on those until late December because of the horrible amount of time shipping takes from there.
Save the seals! no, not the fuzzy kind in the ocean,
I think with the bearing seals removed you will find that after a while, your bearings will be sticking/binding/sluggish from the incredibly fine dust that is generated from the cutting action.
This stuff makes cornstarch and talcum powder look gritty!
The good news is that when they do gum up you should be able to remove and flush them out to clean them and then replace the seals.
If the washers have a burr, couldn’t you just flip them over so the burr is facing away from the seal?
The other thing to do is get a sheet of 600 grit emery and remove the burr.
If you had the tools to make a plug that just fits in a wheel rim like a bearing and the measuring tools you would find 2 things about the wheels you have. 1 the rib in the center of the wheels are not all the shame thickness. 2 the rib on a lot of the wheels is not in the center of the wheel rim.
What this translates to is that some wheels will slide back and forth on the bearings because the washer is thicker than the center rib. The other thing is that if you wind up with wheels that have there center rib not centered and say the left wheel center of the V is closer to the center of the maker slide and the right wheel is further from the center of the maker slide the plate they are mounted to will not be parallel to the maker slide and will give you alignment problems. This really shows up if it happens for the wheels on the top and the bottom of that plate.
Now for the third problem that I have found. If you had a way to measure the angle of the V on the wheels you will find that most of the wheels you have the angle is less than 90 degrees. This means that the wheels only contact the maker slide at the very out side of the wheels. If the wheels are adjusted a little too tight and the machine sits for a period of time the wheels will develop a flat spot and the next time you move the machine you will feel a thump every time that flat spot hits the maker slide.
Hope this helps
Did you receive your ebay v-wheels?
I’m debating between ordering some ebay kits (http://m.ebay.com/itm/Delrin-dual-v-wheel-kits-20-kits-per-pack-free-shipping-DHL-/121831655375?nav=SEARCH), the inventables v-wheels, or the openbuilds v-wheels for a new build. I’ve had good luck with both the inventables and openbuilds v wheels in the past…
I was shaving a little bit off of a sheet of POM-C and you can clearly see the point where the bump happens (the streak in the middle):
I haven’t tried a dial indicator, but it is probably hardly measurable, yet still visible. I have ordered SKF bearings for the gantry, should get them tomorrow. I really, really would not like to take the machine apart now, so it may take some time before I’ll see if the bearings make a difference or not.
So I got my x carve put together up to belting. I did not install the belts yet. I moved the machine around on the v wheels sure enough had bad bumping. I just baught the fiber washers. When I put this back together I am worried I over titened the v wheels the first time any tips on titening just snug? Or go just snug and another quarter turn ? Any advice?