# making a base plate help please ?



## Tazkb (Oct 14, 2011)

OK i'm not generaly thick but I am trying to get my head round one thing, making the hole and lip for the pc type bush's. I am using acrylic, I have 5mm thick and 2mm thick and the way I was going to do it was make the base is this, I have used the Erbauer standard base and coppied that, cutting it out using my rotozip and the circular cutting tool, the way I thought you found the center point was to mount the new base plate on the router and then by using say a V bit gently plunge the router to just pierce the acrylic, I thought that by doing that would make the hole central ? am I right ?
then using the center hole I have just made (only small hole by the way say 3mm?)
then using a forstner bit to sink a rebate to fit the bushing adapter plate. finally i could use any number of bigger router bits to cut the through hole with the new base plate fitted? 
does this make any sense ? because other than this way I cant think of a way of making sure the base plate hole and fitting for the adapter plate would be central
thanks chaps


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## jschaben (Jun 21, 2009)

Tazkb said:


> OK i'm not generaly thick but I am trying to get my head round one thing, making the hole and lip for the pc type bush's. I am using acrylic, I have 5mm thick and 2mm thick and the way I was going to do it was make the base is this, I have used the Erbauer standard base and coppied that, cutting it out using my rotozip and the circular cutting tool, the way I thought you found the center point was to mount the new base plate on the router and then by using say a V bit gently plunge the router to just pierce the acrylic, I thought that by doing that would make the hole central ? am I right ?
> then using the center hole I have just made (only small hole by the way say 3mm?)
> then using a forstner bit to sink a rebate to fit the bushing adapter plate. finally i could use any number of bigger router bits to cut the through hole with the new base plate fitted?
> does this make any sense ? because other than this way I cant think of a way of making sure the base plate hole and fitting for the adapter plate would be central
> thanks chaps


Hi Keith. That's the way I do it, except I use a 1/8" (close enough to 3mm) spiral bit and make a through hole. Basically the same process you just described though,. 
then take the base plate off and use that hole to drill the relief and the through hole. Just drill the relief before you drill the through hole otherwise you loose your reference.


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## Tazkb (Oct 14, 2011)

thanks John,
and how do I cut the lip ? people on here have mentioned using a forstner bit ? but i would need one 62mm in diameter ? the kit i bought was the silverline bushing kit, the brass adapter size is 68mm od with a 62mm lip and 30mm center hole ? and I cant find a 62 mm forstner bit ?


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## BrianS (Nov 7, 2004)

Hi Keith. You can also use a hole saw with good results.


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## Tazkb (Oct 14, 2011)

sorry guys it's just occured to me that making a new base plate I don't need to make a lip to fit the 62mm adapter plate dohhhhh ! I just need to make a lip to fit the the guide bush's which is just over 30mm ? what a thickie sorry guys i'm not firing on all cylinders today


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## bobj3 (Jan 17, 2006)

Hi

Who said it needs to be round. a sq. one works so much better 

Oak Park Enterprises Ltd.: Catalogue

Oak Park Enterprises Ltd.: Catalogue

http://us.oak-park.com/catalogue.html?list=BP-7BP-&product=BP093

http://us.oak-park.com/catalogue.html?list=BP-7BP-

http://us.oak-park.com/catalogue.html?list=BP-7BP-&product=MBK0990

By the way hole saws suck  they are made to cut out a hole not a flat bottom hole. that's needed for the lip of a guide..

http://www.leevalley.com/en/wood/page.aspx?p=41778&cat=1,43000,51208,41778

forstner bits Cheaper than hole saws the norm
http://www.ptreeusa.com/forstner_bit_sets.htm

" Benjamin Forstner patented his forstner bit on Sept. 22, 1874. The successful invention of the forstner bit was to make him a rich man. Without the lead screw (which Forstner calls the "gimlet-point") and cutting lips of more conventional wood boring bits it would prove especially useful to gunsmiths like himself and other high-end woodworkers. The forstner bit was unsurpassed in drilling an exceedingly smooth bore hole, with a flat bottom."
===


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## Mike (Nov 22, 2004)

I use hole saws for this. A lip the width of your hole saws teeth is plenty of support for the guide bushings and since the hole saws teeth are all at the same level it only requires you to monitor the depth of cut. I use mostly Lenox hole saws which have nicely hooked, uniform teeth. Note also the nice hole design on the sides which makes it super easy to pry out the plugs with a screwdriver.


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## Tazkb (Oct 14, 2011)

square bases seem quite popular and as such while I have a chunk of spare acrylic around I fully intend making a square base, as well as a standard shaped one. I have ordered a 35mm forstner bit to cut the lip and allready have a 30mm one to cut the hole. I have no problem with hole saws but the quality varies greatly, cheap ones wobble a lot and you end up with a hole either bigger or slightly out of shape. only the more expensive ones i would trust enough on such a delicate object
thanks guys


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