Anti Backlash Blocks are too tight

Hi everyone! :blonde_woman:t2: I am hoping for some quick assistance! :white_flag: I’m in the middle of assembling my Longmill and have run into an issue. When I ran the first (horizontal) lead screw through the nut block, it could NOT be threaded/go through the block. I removed the block and lead screw and I tried running the screw while holding the nut block in my hand and indeed could not get past the first two threads.

I replaced the block and started again, with no luck. After trying various things, I was able to get the screw through the nut block using a drill. However, once I finished assembling the piece with the coupler, etc…the lead screw could not be turned at all, meaning the router assembly would not move left to right. I took it apart and tried another nut block and it was an easy thread/fix so the router assembly could accurately move left to right.

Fast forward to the vertical rails assembly…both ‘leg lead screws’ are having the same issue I initially had and they could not be threaded without a drill. Once in place, neither lead screw could turn so the router horizontal assembly cannot move back to front. Now I’m stuck and not sure how to proceed/correct the issue. :hot_face: :sneezing_face:

I appreciate any advice/help before I lose my mind! :slight_smile: :brain:

:pray:t2: :woman_shrugging:t2:

@StefiKaye, are you talking about the plastic anti-backlash blocks? Are the screws that go in the blocks loose? If not back them off till they are. You shouldn’t have to use force to get the lead screws through those.

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@StefiKaye Are you talking about the anti-backlash nuts, Stephanie? If so make sure that the set screw is not putting any tension on the nut. Screw them in by hand just until they stop - no further.

edit: It looks like Paul and I were typing at the same time. Great minds, eh, Paul. @paullarson


YES! @paullarson and @gwilki! Sorry, I mean the anti-backlash blocks. I actually removed the tension screws out completely to see if that was part of the problem…so impact/change in resistance. :woozy_face: I will have to try again tomorrow after work and take a couple of closeup pics if still an issue.

Thanks for replying!

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@gwilki @paullarson, I took a short little video this morning to show my dilemma! Hopefully it provides evidence and helps with a resolution!! :nerd_face:

Well…looks like videos are supported so can’t upload it here. I saved it to my Dropbox account so you could review.

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@StefiKaye This may well be repetitious, but it’s just so darn good, that it’s worth repeating. :grinning: :grinning:

I know that you said that you took the nut off the machine and it still threaded tight. Was the set screw out entirely when you tried that? If so, then I think we can conclude that the nuts are faulty.

If not, there is still hope.While the nut is on the machine, loosen the two screws holding it to the machine so that it can slop around a bit. Then try pushing the lead screw through. If it goes, get the lead screw fixed at both ends, then tighten the screws holding the nut. Only then can you tighten the set screw on the nut to take out any backlash.

If none of this works, write the Andy and/or Chris. They will make it good.

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@gwilki I’m on it! I’ll let ya know how it goes!! Wish me luck! :shamrock: :four_leaf_clover:

@StefiKaye, if Grant’s idea doesn’t pan out, here’s mine. When threading the rod through the rod through the anti backlash block keep in mind that there are two threaded sections that you have line the rod up as you screw it in. I’m wondering if you threaded the rod through the first one and then it wasn’t aligned with the second one so it hung up. The anti backlash block in the video looks a little chewed up. You might consider ordering more from Scienci. I don’t think they cost much.

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i have my fingers crossed that this does not turn into a not-quite-v delrin wheel situation but i just got my machine today and those threads on anti-backlash nuts do look a bit chewed up right out of the box. i hope to be where @StefiKaye is in the assembly process before midnight pacific and will be sure to holler if my assembly stalls similarly.

My anti-backlash nuts were fine apart from the lead screw threads being a little ugly around the edges. My trouble ended up being it was WAY harder than ‘tapping with a mallet’ to get the lead screws through the bearings.