A new way to think about frame size and angle

I designed the new frame to allow adjustments of the frame angle between 15 to 5 deg. …

our current tests tend to assume, that 11deg. is perfect… at least we could improve accuracy … our sled weight is about 12.5kg, motor distance 2952mm and distance to work area 505mm. The sled doesn’t tilt when its center reaches the edge of the working area by using bodybuilding weights of 2.5kg each. With bricks of same weight cog was different and sled tilting + its top never touched the working area…

sorry, is this the result of testing? or where you plan to start testing?

Our new frame is currently planned to have a top bar of up to 3700mm and a total height of 2500mm with a adjustable skirting of 100mm around the work area…

could you experiment with the skirting? My belief is that no skirting on the top
is needed, the sides can use narrow skirting (50-100mm) and the bottom needs a
lot of skirting (150-200mm)

I would see how close you can cut to the edge without any skirting, then make
the skirting just a little wider than that.

Further we have planned to return back to bottom feed and introduce a chain
tensioner using some springs, similar to barn door springs, but integrated in
the hollow space of the top bar to achieve I.e. dust protection.

springs have the problem that they produce the most force when you need the
least, and the least when you need the most. weights provide a constant force.

If you want to make everything super slick, route the tension lines through the
tubes to weights in the legs (but it probably requires a lot of pulleys to do
that, having the lines just extend out past the workpiece and then drop down,
with pulley’s or just plumbing sweeps works well)

David Lang

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This is the data of the current frame we are using and our findings from testing by means of frame angle …

Currently we had been as close as 2cm to the bottom and top edge in the center area with good accuracy, but such is lost, once we are even 20cm off the left/right edge …

Thats why we decided to build a new frame with a top bar at least 3600mm and a frame height between 2250mm to 2500mm (skirting all around 100mm = 100mm bottom + 100mm top + 1250mm working area + >800mm distance to motors = > 2250mm …

Thank you for your advise … OK, we will experiment with some pulleys! :slight_smile:

Boris

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@buhlig How are your tests going with the larger frame? I’m very interested in your results. :slight_smile:

Vielen dank,

-Jeff

Hey @JWoody18, we ordered the UA Profiles and accessories, which are expected to be received next week … keep you posted in due course! Bis dann …

Any updates on this? I am planning on building a 14’ top beam 30" above the work surface with a 10 degree tilt tomorrow. If that’s been done already, I would love to learn about it.

we successfuly upgraded to a 360cm top bar, 90cm above working area with a 11 deg tilt. first tests went fine. about to cut the first chair

Sweet! Let me know how it goes. I am building the new frame right now.

I misspoke before. I am going to be building a 14’ top bar, 28" above the work surface. Hoping this gives me optimal results, assuming I can get it to calibrate well.

Here is a 14’ top rail 28” above the work. I am routing the chain tenders via pulleys to the back side and using lead ingots in milk jugs as ballast. I haven’t run it yet, so there will be some tuning needed still.

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Another photo with everything connected.

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Looks great, how did the test runs go?

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Went well, but not perfect. I still get wavy lines when moving from center towards the edges, within 12" of the right or left extremes. I am going to try adding more weight to the sled and see if that makes a difference.

That said, it made a big difference compared to the original 10’ frame which was completely unusable within about 20" of the right or left edge.

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try to make the bottom of the sled slicker.

note, changing the weight will affect calibration.

David Lang

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congrats on the improvements, even if not perfect yet. How much does your current sled weigh? Double check the spread sheet but Im pretty sure you can go as heavy as about 27 to 30 lbs with that big of a top bar.

to support a heavier sled, you need a higher top bar (to reduce the max tension
on the chains in the top center), not a longer top bar.

David Lang

26 lbs looks good to me if you have 36" height.

Thanks @dlang and @Metalmaslow, appreciate the experts weighing in.

@dlang, I am using a kit by Maker Made which came with a pre-fabricated sled. The roundover on the edges is good and the plywood is pretty fine. I did put a bit of dry lube on it, which is a parafin lubricant. It didn’t seem to help all that much. What do you suggest for improving this?

@Metalmaslow, The sled is currently about 24 lbs and I have plans to bring it to about 28 lbs. I could go a bit heavier, but 28 lbs should be the sweet spot in the custom geometry that I have built. I am noticing that when the sled is moving from the edges toward the center within about 12-18 inches from the edge, the cuts are smooth. Moving from the center towards the edge is where I get some wavy lines. It’s not terrible, I will post a photo on my next post.

I would use UHMW on the base. https://www.amazon.com/TapeCase-423-5-UHMW-Tape-Roll/dp/B00823JFAI/ref=sr_1_10_sspa?keywords=uhmw+sheet&qid=1583429704&sr=8-10-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExVkhNUzVJR0FZTFIxJmVuY3J5cHRlZElkPUEwNTgwNTQ2MlNRSUpBUzNDUTI5MyZlbmNyeXB0ZWRBZElkPUEwMTQ5MDY0MVlLUFNIWkpQNlJPSCZ3aWRnZXROYW1lPXNwX210ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

I got some UHMW in and will be trying this soon.

OT: May i ask which kind of vac you are using so i can look up how “strong” it is? Does the vac system work sufficiently?

Hello,

reading through most of the thread i must admit that its not entirely clear to me which dimensions work best. I would be glad if someone could give me some advise on how to best modify my current frame.

Currently i have an 12" top bar frame with the top bar placed 67cm/26.4 above the work space. My sled is a bit heavy with 13kg/28.6lbs (stock, “old” metal maslow sled with metal maslow z-axis and Ridgid router). The angle of the frame is unluckily 10-11 degree even ive given the instructions/drawings to make it 14-15 degree.

As i dont want to change the height of the top-bar, is it better to stay with a 12" top bar or replace it with a 14" top bar? I need to replace the top-bar anyway as the used alloy is not strong enough.

Thank you!