Key design points for Low Rider 4 table

LowRider CNC Advice
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This is my first post. I want to build a table for the Low Rider 4 that can handle a 4’x’8 plywood. I would like to do through cuts as well as dados for shelving.

I’m really impressed with the concept of the LR4 and can’t wait to get it built. I’d love some critique of what I’ve gleaned as the key design points of a table.

Key design points for Low Rider 4 table: (From most important)

  1. Base + table + rails need to be stable with very little flex.

  2. Y axis drive rail:

    1. Needs to be straight as seen from top view (to make straight cuts)

  3. The y drive rail and y idler path surface need to be parallel as seen from side view.

    1. If these are not parallel, at some point we start racking the x axis gantry. What are the consequences when this happens?

  4. Smooth surface for y idler path.

  5. To a lesser degree (because the surface grinding of the spoil board will correct some errors)

    1. Flat torsion table top that supports the spoil board

    2. Flat mounting surface for y drive rail (straight from side view)

Any critique and advice are appreciated.

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Welcome in.

I am not sure what are you asking for?

1-Ideally, but there is also plenty of room for error. Topics tagged parametric-table

2-Yes, easy to do. Shown in the instructions.

3- The rail is all that matters, the rest just need to be as close as you can get it.

4- ??

5- Actually does not matter much unless you are surfacing thick slabs or something, then yes shim your table as flat as possible.

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Thanks Ryan. I’m in the early stages of a table design and wanted to make sure I was understanding the key things to consider in my design. Thanks for the link too.

I may be overthinking how accurate the table and rails need to be.

My comment #4 was just mentioning the surface the idler side of the gantry rids on should be smooth. (no bumps caused by a joint for example)

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i built my LR4 about 2 yrs ago , mainly for timber slabs, i new absolulty nothing about cnc

i have since changed to doing more custom cabinetry

as i come from building background my table is over kill, using 6 x2 for table top frame ,storage cupboards supporting frame on a 4 x 2x 3mm steel base with castors as some slabs over 100kg

dependent on your workshop set up and humidity you are always going to get contraction and expansion in table even after i sealed my mdf table top both sides with a 2k sealer there is movement

its not noticeable in finish cuts as generally cutting right through material with cabinetry

I use 4.75mm mdf as spoil board, new one about every 12 sheets, for me it works out better just throw it on table than sheet to be cut on top slots or dados generally 0.5mm variance in depth for an 18mm sheet i set doc at 18.7mm

as far as setting up y rail and belt I used laser to set mine square

2.1 getting straight cuts

from my experience its more user error than the lowrider , the dumb things i did when learning The LR4 handled it all eg thinking i had put in 1100mm/m federate when had put 11000/mm/m

the right tool , ,right feeds and DOC, get them wrong and its amazing how it will give you wrong finished sizing don’t buy cheap tools , i only buy custom made tools now that can be reground

i run at 1700mm/m at 6.3 mm doc on laminate mdf and get clean straight cuts

i find partial board the worst on sizing , think its the glues seem to pull the tools inwards as u get deeper , i have to leave 0.5mm stock to get right size , mdf same tool cuts exact to size

currently doing a big display cabinet with so many angles , tops and bottoms, variance between both pieces was around 1mm max , can throw up photos later when get to shop if you want

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Thanks Terry for sharing your experiences and tips. I look forward to learning to use the cnc as well.

A follow up question on your success with dado cutting. You achieved around .5mm variance in dado depth. That sound reasonably good. Is that achievable over the whole work surface? Also, do you re-surface the spoil board each time you replace it?

My cnc will be in an air conditioned space, so hopefully I don’t get a lot of expansion & contraction.

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no worries

by this do you mean say you are doing various slots on various pieces which are spaced out on the sheet , yes, I cut piece other day 1700 x 700 with a opening in middle of 515 x 1580 and than a pocket right around internal opening 10 mm wide x 9mm deep for a glass panel to sit in , pretty dam accurate finish. end of day , i doubt the depth of dados wont be visible so any small variance wont be noticeable anyway

no, once i had built my table I machined the top prior to 2k sealer so that is pretty accurate, hence why only use 4.75 mm as variance in that size is basically nil , i did a trial surface on a sheet one day set tool 0.2mm above sheet it touched sheets in couple of spot that was prob cause it was just lying there the weight of an 18mm sheet holds it down

what ive found is you need to go at least .8mm into spoil board to get clean edge especially with harder acrylic laminates , so after cutting a few sheets the spoil board has raised spots. i use a 6 inch scraper to knock of high spots, if to many lines 150g on sander than flip it over, I add cost of spoil boards on to my quote so customer pays so I’m not bothered about how many i go through

honestly if you are generally only going to be using ply , nothing will be noticeable , I used to do a lot of kitchen renos and at times install high end cabinetry. Gloss white is the worst as far as being noticeable and you would think for the cost of some of it ,it would be exact , not even close the variance could be up to 2mm in panel width and height, if your like me that does my head in seeing it , end of the day maybe 1 in 20 customers will notice it

installed a kitchen once and draw handle screw holes had been drilled off centre from factory, customer had supplied cabinetry so i just installed it , it looked so stupid , customer never noticed it , she was just happy to have new cabinets

jealous on that one

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I understand what you were saying previously: You surfaced the table top, which enables you to simply replace the spoil board which has a very consistent thickness. That makes a lot of sense. Thanks.

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did i repeat myself , sorry bad habit of doing that