V Wheels Question


My right v wheels are not sitting fully on the rail, but the machine jogs perfectly well.

Is it just me or are they not sitting fully?


@Bizbrar It’s not just you, RB. At a glance, I would say that they are not set tight enough. If you lift up on the gantry a bit, are they tight to turn by hand? Are the bottom ones tight?

Take a look at this youtube video by Chris to get the details on setting them up and report back:

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Chris, as a retired certified tool tech, most manufacturer’s will give a tightening guide in inch pounds and a inch pound torque wrench is
inexpensive. Thanks, Art

@Art Art: I know that you directed this to Chris, but I think the problem with your suggestion is that there is nothing in the V wheel setup that relies on how tight the eccentric nuts are in inch pounds. I have torque wrenches, but I can’t see how any of them could measure the “tightness” between the upper and lower V wheels or between the V wheels and the rails that they ride on.
All that said, I am not a tool tech, so I could be missing something quite fundamental here. I’m open to learning, though.

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Although I agree with what you’re saying, I feel it would be more helpful to know the recommended torque settings for all hardware, and not just the V-wheels’.

Getting back to the OP’s question, though, to my eye it appears that the spacers between the wheel and the bearing are either different sizes or perhaps one was added (or not put on…). Should be a simple thing to check that out.

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Grant, thanks for the opportunity to share my thoughts. My longmill is not in my hands yet so I am not acquainted with the specifics. In my experience, every tool I opened up with values from $80. To over $20,000. was repaired or refurbished with a schematic alongside due to constant changing updates affecting torque values and other parts regardless of the manufacturer . This is my experience talking of 45 years of training and maintenance . I have never seen a open dialogue between a manufacturer and the end users as you have here and I applaud your desire to listen!
. Thanks, Art

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@Art Tks much, Art. I’m not a professional anything. :grinning: I am big on using torque wrenches, though, and have several. When you get your LongMill, I’m sure that it will be obvious to you that, although torque values for some of the fasteners would be good, setting the “tightness” of the V wheels really can’t be done with a torque wrench. What we are trying to accomplish by adjusting them is to find a sweet spot where the upper and lower wheels are pinching the rail just tight enough to let them move smoothly - not so tight that they bind, and not so loose that we lose precision. That kind of talk must be like nails on a chalk board to someone with your training and experience. :grinning:

I would be interested in your thoughts about setting torque values when using nylock nuts. I’m sure that it is possible, but I’m also reasonably confident that the tolerances on these mass-produced nuts are not that tight. So, it could be possible that before the bolt is tight to a torque spec, the resistance between the nylock nut and the bolt could trip the torque wrench. Also, as I’m sure you are aware, each time a bolt is loosened and retightened in a nylock nut, the friction between the nylon and the bolt decreases. Would that change how a torque wrench behaves, do you think?

Yes, I agree. The big question is supplier??? A German product arrives with German parts. Specifications are tight. Due to natural disasters like tusonomi in Japan, manufacturing in Japan was moved to China and in the last years a small combustion motors regardless of manufacturer came from the same plant in China creating a crossover of parts that is very complicated and lately companies like Briggs and Stratton are returning to America for production. I was extremely fussy about importing bearings and Turkey was my choice due to tolerance controls. My company account with Fastenal in Wasilla Alaska was 004 one of the first in that area but further inspection of their products showed a questionable end product for fine workmanship. I quickly realized that “it will work” versus “perfect fit” was not a question when the tools we repaired arrived and returned by airplane throughout Alaska and also working on Military bases perfection in quality parts and exacting labor practices created a lasting impression on our little 5 person shop with multimillion dollar companies. I demanded perfection from myself and my employees shoring up our credibility in the market place. I believe Sienci is doing a great job in updating every query to assist the customers. That is my opinion and I will stick to it. Art

Thanks for this. I’ll try to adjust per the video. I’ve already screwed the Y axis to my table, probably should have fixed the v wheels first.

@ApexWoodworks the spacers are the same on both sides.

Could it be that the wheels on the opposite end (but at the bottom) need to be tightened, and it would “pull” the side in the picture closer?

@Bizbrar Your installation order is correct, RB. You want the rails screwed down and squared before doing the final adjustment of the wheels. The rails being parallel to each other and square to the X gantry is critical.

As to your question about the wheels at the opposite end, the bottom wheels cannot be “tightened”. Only the top wheels on each of the gantries can be tightened/adjusted. Changing them, of course, changes the bottom wheels.

I use a small wedge to support part while adjusting the v-wheels. This allowed me to align the upper wheels

I do similar as Lawrence does, but use a bolt and a nut. I adjust the nut to just take the play out of the bottom wheels, and then adjust the top wheels. It seems to work for me at least.

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Thanks for the replies

I will try to loosen the bottom wheels then try to close thr gap by tightening the top then.

Hope it works!

@Bizbrar RB: There is no adjustment in the bottom wheels. You don’t want to loosen the bolts holding them. All the adjustment is done from the top wheels.

Gwilki: Regarding your statement… “You want the rails screwed down and squared before doing the final adjustment of the wheels. The rails being parallel to each other and square to the X gantry is critical.”

How about Sienci offering a paper template for the proper location of the rails on the baseboard?

@R.Portman Welcome to the forum, Roland.

I can’t speak for Sienci on the subject of providing a mounting template, but I can say that there really is no “proper location” for the rails on the table top. You can mount the rails any way you like on your table top, so long as the Y rails are parallel to one another and they are square to the X gantry. You may have already seen this, but here is the Sienci instruction on mounting the Mill to the table:

As you can see by that article and as you’ve likely determined through your own experience, you could mount the Mill diagonally on the table top if you wanted, again so long as things are parallel and square.

In terms of getting things square, here is one thread on this forum on a method to square things up:

If you search this forum for “square”, you will find several others.

I hope this replies to your question. If not, please explain how you think Sienci can improve on this and I’ll take it up with them.

I had the exact same problem and took the same picture when building my Longmill. By loosening all the bolts that hold the black steel end support piece to the aluminum X rail, the wheel settled into place. Carefully retightening all the screws then held the assembly exactly square and the wheel sat perfectly on the Y rail.

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I loosened as recommended and then hand tightened the bolts and it worked perfectly. Can finally proceed with testing.

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