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Drill Press Lags with Forstner Bits??

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Forum topic by WoodSimplyMade posted 09-26-2011 04:12 PM 2119 views 0 times favorited 12 replies Add to Favorites Watch
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WoodSimplyMade

188 posts in 1973 days


09-26-2011 04:12 PM

Topic tags/keywords: shop drill press tools forstner bits pulley power fix problem

Hey all!

I have an older hand me down drill press, back from when they were made from precast iron, its a bench top model and works like its brand new. It has the pulley system which I have played around with, and I think I have the pulleys set up to produce the most amount of RPM’s, however, using larger 1.5”+ forstner bits it lags and pretty much stops.

I slowly lower the bit into the wood (all types) and it slowly begins to slow down and then stops almost removing no wood at all. The belts do not slip so the motor isn’t still turning so I am guess the motor may be too weak.

Any suggestions and procedures on how or where to fix it would be helpful. I would like to keep this drill press because mechanically they just arent built the same anymore.

Thanks,
Mike

-- Mike, Florida, http://www.woodsimplymade.com


12 replies so far

View Murdock's profile

Murdock

107 posts in 1137 days


#1 posted 09-26-2011 04:16 PM

If I am reading this correctly you have the drill press setup on high speed?

You need to slow down the drill press for big bits.

Here is a bit speed chart that I use for reference:
http://images.meredith.com/wood/pdf/drill-press-speed-chart.pdf

-- "Anyone who has never made a mistake has never tried anything new." - Albert Einstein

View Bill White's profile

Bill White

3453 posts in 2614 days


#2 posted 09-26-2011 04:18 PM

Need more info. What’s the HP of the motor? What RPMs are ya runnin’? Are the bits sharp?
I run my 1952 Craftsman cast iron monster at 600 rpms for most drilling in wood. Other speeds according to what I’m drillin’.
Bill

-- bill@magraphics.us

View WoodSimplyMade's profile

WoodSimplyMade

188 posts in 1973 days


#3 posted 09-26-2011 04:19 PM

Murdock,

Yes I have it set on high speed. I will try to slow it down and see if that works, it just seems there is no power behind the bit though? Bits are sharp and new.

Thanks for the chart will print and keep this!!

Mike

-- Mike, Florida, http://www.woodsimplymade.com

View PurpLev's profile

PurpLev

8476 posts in 2302 days


#4 posted 09-26-2011 04:19 PM

small drill bits = high DP speed
large drill bits (forstner) = slow DP speed

slow your DP… sounds like you set it up much too fast.

-- ㊍ When in doubt - There is no doubt - Go the safer route.

View WoodSimplyMade's profile

WoodSimplyMade

188 posts in 1973 days


#5 posted 09-26-2011 04:22 PM

Bill White,

I probably should have looked to see what the HP was before posting this, I will have to check when I get home tonight.

Sounds like I need to slow down the RPMs I am running. Not sure how to tell the exact number from the pulley system.

-- Mike, Florida, http://www.woodsimplymade.com

View PurpLev's profile

PurpLev

8476 posts in 2302 days


#6 posted 09-26-2011 04:26 PM

Mike, the way the pulleys work on a DP is that when you set it at high speeds the motor does not transfer as much torque to the drill bit but it does turn it faster. when you set the pulleys to slower speeds it then transfers more torque from the motor to the drill bit albeit not at a fast turning speed. This is why the larger the drill bit the slower you want to set your DP as the larger the bit the more wood/material it has to bite into and the more torque it requires in order to keep it turning. if it doesnt get enough torque from the motor it just stops – as you’ve experienced.

-- ㊍ When in doubt - There is no doubt - Go the safer route.

View WoodSimplyMade's profile

WoodSimplyMade

188 posts in 1973 days


#7 posted 09-26-2011 04:30 PM

Thanks for the explantion PurpLev, you learn something new everyday. I almost went and bought another drill press lol. Glad I have my LJ community to turn to before making dumb decisions.

Thanks again, will try this when I get home!

-- Mike, Florida, http://www.woodsimplymade.com

View dbhost's profile

dbhost

5383 posts in 1885 days


#8 posted 09-26-2011 04:37 PM

Wood Magazine publishes a drill press speed chart that will help you figure out what speed to set your DP at for the best cutting with specific bits. I printed one out, and put it in a clear plastic sheet protector that I have tethered to my drill press for easy access. Spinning a big bit too fast will stop your drill press cold.

-- My workshop blog can be found at http://daves-workshop.blogspot.com

View WoodSimplyMade's profile

WoodSimplyMade

188 posts in 1973 days


#9 posted 09-26-2011 05:02 PM

Thanks dbhost!!

-- Mike, Florida, http://www.woodsimplymade.com

View WoodSimplyMade's profile

WoodSimplyMade

188 posts in 1973 days


#10 posted 10-09-2011 05:12 AM

Thanks to all who posted solutions, and an update for anyone reading this forum, I did exactly as everyone recommended and changed my pulleys to run on a lower RPM and now my forstner bits drill great! Thanks again everyone!

-- Mike, Florida, http://www.woodsimplymade.com

View Brandon 's profile

Brandon

197 posts in 1320 days


#11 posted 10-09-2011 07:40 AM

Thanks dbhost I just printed that out!

-- An investment in knowledge pays the best interest. Benjamin Franklin

View David Grimes's profile

David Grimes

2072 posts in 1293 days


#12 posted 10-09-2011 09:54 AM

Don’t be shocked if it has a time with the large forstners even with the speed down all the way. Go slow and raise to clear often. I have a nice bench model that has difficulty if I try to drill out hidden hinge holes too quickly even after I have it set at the lowest speed. Some table models’ charts don’t even go over 1” diameter (for a reason). It will do it, but you must go appropriately slow on your lowering as well.

-- If you're going to stir the pot, think BIG spoon or SMALL boat paddle. David Grimes, Georgia

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