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Router bit and Router size for CNC?

6771 Views 17 Replies 5 Participants Last post by  macg
Router bit and Router size ?

I want to cut some grooves with a 3/4" ball nose in MDF can anyone recommend the size router I need and what cutter size to get, I am planning to build a cnc from MDF and the plans call for this size, see rockcliffmachine com the grooves are for bearings, the plans say to use a table router or table saw to cut the grooves, I do not own a table router and want to buy one for other projects too.
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At the top of our home page you will find a link to Oak Park, the home of The Router Workshop. You can purchase one of the best tables available there. You should have a router with a 1/2" collet, for help in choosing a router click on the blogs link and select Sawdust Dreams. You will find a wealth of good common sense information there to help you along. To cut a 3/4" groove you need a bit with a 3/4" diameter. Usually people would use a straight or plunge bit for this process, not a ball cutter. Is there a special reason you want to use the ball cutter bit?
Hi macq

Looks like you will need two ,3/4" and 1" If I readed the PDF file right.

Core Box Bits
#8718 3/4"
#8719 1"

Bull Nose bits
#7764 3/4"
#7765 1"

Bj :)
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Thanks for the fast reply
I am trying to build this see a picture rockcliffmachine com it's a CNC router made from MDF or wood the bearing grooves call for grooves to be cut in the table slides for a 3/4" diameter bearing it can be a round, a vee or a straight groove I thought the round grooves would fit better. I cannot seem to insert a picture or link to this post
I looked at Oak Park but I cannot find the 3/4" ball nose bit, is it available ?
You are not allowed to post links until after you have made 10 postings, this is to prevent spammers and such from posting junk. It would be best to cut a straight groove.
I was hoping I could use a smaller trim router to cut the grooves, then I could use the same router and mount it in the cnc machine , is it possible to get a 3/4" straight bit with a 1/4" shank and if possible would a smaller router be able to cut these grooves in mdf?

W e l c o m e . . A b o a r d !!
yes the core box bit looks good #6418 , I have been looking for a ball nose all this time, why is it called a core box bit? the plans call for the 3/4" dia. grooves to be cut 3/8" deep, it might be slow going with a smaller 1/4" collet router, but if I can do it I will be able to mount the router in the CNC machine I am building
core box=

The most important part of a thing; the essence.

The portion of a mold which shapes the interior of a cylinder, tube, or other hollow casting, or which makes a hole in or through a casting; a part of the mold, made separate from and inserted in it, for shaping some part of the casting, the form of which is not determined by that of the pattern.

The center or inner part, as of an open space; as, the core of a square.

A projecting piece on a pattern which forms, in the mold, an impression for holding in place or steadying a core.

Bj :)

macg said:
yes the core box bit looks good #6418 , I have been looking for a ball nose all this time, why is it called a core box bit? the plans call for the 3/4" dia. grooves to be cut 3/8" deep, it might be slow going with a smaller 1/4" collet router, but if I can do it I will be able to mount the router in the CNC machine I am building
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Trim routers can be purchased for as little as $12 and yes, you get what you pay for. The Bosch Colt trim router is top quality and you will need to add more than $100 to that $12 to get one. Since you are interested in CNC routing here is a link to view one of the most common CNC router applications. This uses a Bosch 905:
Wow thanks you guys have really been helpful to get me back on track, I have seen some really low cost trim routers out there, and it has been tempting, but I will for sure look at something with more quality, and one that can be table mounted, the final use will be used on my CNC Router but I am sure I will find a use for it when mounted into a table , a table router sounds like a great tool for any woodworker, made from MDF CNC Router I am building can use a 5amp trim router with 1/4" collets

Hi, Macg: A 1 1/2 HP router should do it. It will handle a 3/4 " bit with no trouble.
If you don't have a router table, you are going to need a guide to mount onto your router to kepp the cut straight. If the MDF is 3/4" thick or more it would be a good idea to take it in 1/4" cuts until u get through the material. Since you are going all the way through don't for get to place some scrap material under the mdf to avoid damage to you bench or whatever you are using. Hope this helps Woodnut65
Hi Woodnut65
the CNC machine I am making is made from 3/4" MDF
see rockcliffmachine . com the grooves are only 3/8" deep
I know that a trim router is small for the job but I want to use the trim router later in the cnc machine, the cnc machine I am building has only the capacity for a smaller trim router or dremal tool.
Hi macq

You may want to back off with the "dremal tool" they are made for light duty, I have a router bit set (1/8" shank ) for the Dremel but they will cook bits in a heart beat,the VS Dremel will help but then you have no power to do the job :) ...
rpm = HP they spin at 30,000 rpm the norm.
You may want to take a hard look at the link below, this tool will come with all the add on items you can use to get the job done.
Most trim routers don't have or come with the add on items at a good price.
I have one and they do have the power to run most 1/4" and 1/8" router bits.

Marvel 40 3-in-1 Router Kit

Good Luck with your CNC setup you are about to take on a big JOB :)

Bj :)
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hopefully I will get it right here's the plan I am going to try and cut the 3/4" grooves (MDF CNC MACHINE only 9 table slide grooves needed) with a 3/4" core box bit #6418 with 1/4" shank I will cut the grooves 3/8" deep in MDF with a small trim router mounted in a table as a table router with a fence for guiding.

it sounds like you guys agree it might be possible to cut the 3/4" grooves with a smaller 1/4" collet trim router
We have home depot and lee valley for tool selection up here in canada I think the core box bit will be the hardest part to get, we have a good selection of routers Bosch, dewalt, hopefully I can buy the cutter locally too
Does anyone know where in canada I can buy a core box bit 3/4" diameter with a 1/4" shaft ?
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