Holding Material Down for Machining

[gene35146]

I have been looking for better ways to hold stuff down to my spoiler board than the clamps.  I have seen a lot of videos where they use hot glue and have tried it and that works good although it can be a little pain to get off it you put too much which I did the first time.  While surfing youtube I found this little gem of a tip.  I couldnt believe it works the guys uses masking tape and glue with an accelerator and then the tape pull right off.  

[Deleted]

You could use composite brads and just nail it to your spoil board. You can machine right through them without hurting your bit and when you're done you can break them or drill them out to detach your work piece.

raptornails.com/

redhawkfasteners.com/index.php

[gene35146]

I am going to give this a try, I need to make new spoiler boards anyway so will let you know how it goes. No sure if the nails only work with their nail gun or not?

[Deleted]

Raptor explains on their site somewhere that you need to use their gun because it has tighter tolerance and supports the brad better during ejection. But they also say that others have tried guns that have worked to varying degrees and that other some guns jam more than others. The brads are cheap enough that it's worth trying in your gun. They're also good for people with scroll saws that want to cut multiple pieces at once in a stack up. If they do work well with your gun please let us know which gun you're using. When I get around to it I'll get some for my gun and try them.

[jordandemoss]

What about the clamps do you find insufficient?

[gene35146]

They only work for certain height material, if you use the front x/y there is no room to clamp in the front and down the sides. You must be extremly careful to make sure that they never get close to the path you are machining. Try clamping a piece of 24 x 48 material to flatten it. Just lots of things.

[Deleted]

Jan 26, 2017 20:47:38 GMT -5 gene35146 said:

They only work for certain height material, if you use the front x/y there is no room to clamp in the front and down the sides. You must be extremly careful to make sure that they never get close to the path you are machining. Try clamping a piece of 24 x 48 material to flatten it. Just lots of things.

Yeah, holding down the middle of an arched piece is a pain. Then you may have to use a down cut bit an they have issues with clearing the swarf.

[Adillo303]

I watched this video and liked the clamps.


I watched anothet video where someone made non standard dowels on his cnc.

I bought Greg's plan for a buck. It is a pdf. I vectorized that, layed out 6 clamps. I also made knobs. Next to make the dowels ( they will be 1/2". All I will need to buy is carriage bolts. The clamps look pretty versatile.

[Deleted]

I've found that maple or oak hardwood flooring can be very useful for making hold down clamps. You can use the tongue or cut off the bottom half of the groove and put a slot in the middle for a bolt to use with a T-nut. Wider 4" or 5" boards can be cut across the grain and make nice short clamps. A plus to these is that you can machine into them without much harm.

[Deleted]

CNC Nutz has some for free he makes from scrap:

[gene35146]

I have tried a lot of different things. I have tried the vacuum systems you can buy from Axiom but didn't have much success. I got a two vacuum pads that I bought from Lee Valley that I have not had a chance to try out yet. I looked at a full table vacuum but it was nearly $3K to buy one for my AR8 which is ridiculous. This weekend I went back to basics and machined new spoiler boards with 20mm and 3/4 bench dogs in them. I broke the spoiler boards into two parts one 30" and one 19" so I could machine them without moving the boards. I found a source at bolt depot for the nuts and bolts to use. In one thread there is a hold down clamp so I am going to make one of those that can be put in the front and see how that works as well.

Attachments:

[pomeroypap]

Feb 14, 2017 11:05:36 GMT -5 @fean said:

CNC Nutz has some for free he makes from scrap:

I like these.  Who is CNC Nutz?

[Deleted]

May 1, 2017 14:32:04 GMT -5 pomeroypap said:

Feb 14, 2017 11:05:36 GMT -5 @fean said:

CNC Nutz has some for free he makes from scrap:

I like these.  Who is CNC Nutz?

A guy from down under that has a Youtube channel for the CNC machine he made and related projects.

[Deleted]

For side clamping these are nice:

[oldgrowth]

I was going to post about the dog holes I created in the spoil boards, and in searching posts I see that gene35146 already posted something similar. Well I'll post a picture anyway. This isn't a hold down/clamping solution so much as it is a way to facilitate squaring up your material to the xy axis.
For anyone interested in doing the same, make sure you tighten down the fasteners on your spoil boards before doing this, and on a regular basis. I use the dog holes to square up my work piece. However after using this for a few months I found my panels weren't perfectly square as they had been. I checked everything and found that a couple my spoil boards had moved slightly! 
To square it all up again would've been a nightmare since they will move in all directions when loosened. Therefore I loosened and aligned them and made up a new tool path to fit the open areas, while maintaining 20mm holes, 96mm apart on center. Had to move some rows to get more rows of dog holes, but that worked fine.
I used a black marker inside the old holes so I know not to use them for squaring material. 
Now I can square up my material once again. I just make sure to cinch down the spoil board fasteners every week. Eventually I'll probably remove them one at a time and add a drop of Locktite.